Angels

"You, celestial being, are an angel of the Lord."

- The inner "programming" of an angel

Angels are celestial beings created by God. They are winged spirits native to Heaven, imbued with holy white light. And although both angels and humans were created by God, angels are very different and are supernaturally superior to humans. Their true form is nothing less of holy righteous beasts, ranging from two to six feathered wings, four animalistic heads, and can be as tall as skyscrapers.

Early History
Sometime after God and Death's existence, God creates Heaven. He later creates the first beasts, the Leviathans, and let them roam Heaven, eating and devouring everything in their path. Death found them entertaining, but God was concerned for the sake of the "petri dish", so he locked them in Purgatory.

God later creates perfect creatures, the archangels (Michael, Lucifer, Raphael, and Gabriel), the first type of Celestials. Metatron, the fifth archangel and scribe of God, was created at an unspecified time. However, Metatron was present and was recording the events as God was proceeding with creation. Soon afterward, God makes the Seraphim, angels and Cupids. After a while, God then creates the Earth (what Lucifer calls His last great "handiwork").

Lucifer was God's favorite creation, but once humanity dawned, God makes them his most beloved, which infuriates Lucifer. He attempts to covince God of their flawed nature, but God doesn't listen. Then, he entreats to Michael, but he won't disobey his father. Lucifer then begins a rebellion, trying to overthrow his father, but Michael leads the host of Heaven, and defeats Lucifer. Gabriel can't stand the constant arguments, so he flees to Earth, posing as The Trickster. Lucifer goes to Earth and corrupts a human soul, Lilith, into the first demon. This angers God, and Michael, on God's command, casts Lucifer into Hell, located in the deepest part, locked with 600 seals, 66 of which needs to break for his release. A prophecy states that one day Lucifer will break free, initiating the Apocalypse, and that Michael will kill him and bring paradise to Earth.

Castiel and his Garrison watch the first humans construct and build, and animals "heave" themselves on a beach. Castiel's immediate Garrison - Anna, Uriel, Hester, Balthazar and Inias - are stationed to protect and watch the Earth. They watch and wait in silence for thousands of years, hearing nothing from God or their superiors in Heaven.

In 1970s, the Angels secretly arrange for John Winchester and Mary Campbell to fall in love and conceive two children: Dean and Sam Winchester.

Season 4


In 2009, Castiel is sent to rescue Dean from Hell. He leads a siege against Hell's fence, which Uriel was a part of. Castiel successfully saves Dean, but not in time to stop him from breaking the very First Seal. On Earth, the Angels try to stop Lilith from bringing about the Rising of the Witnesses, but they fail, and another seal is broken. When two witches prepare to summon the demon Samhain - which will break yet another seal - Castiel and Uriel are sent to destroy the town to prevent Samhain's rise. The Winchesters, however, refuse to let them kill everyone in the town, and set out to stop Samhain's summoning themselves. Unfortunately, they fail to prevent the summoning, and though they defeat Samhain, the seal is already broken.

Fallen Angel, Anna Milton, is on Earth, as she "cut" out her Grace (Angelic energy/core which supports their power), is in a ward. She can hear Angels speaking, and escapes. After much searching, Alastair, a Demon, finds her and is accompanied by two demon brutes. But Castiel and Uriel arrive, and they showdown. Uriel easily dispatches both of Alastair's guards, and Castiel is overpowered and apprehended by Alastair. Anna regains her Grace, and becomes a full-blown Angel again. In consequence of her consuming her Grace, intense light leaks out of her eyes, and envelopes the room, destroying Alastair's vessel.



The Angels manage to save a Seal - in this case the attempted killings of two Reapers - by tricking Sam and Dean into investigating a town where people have stopped dying. In addition, they capture Alastair. Around this time, seven Angels from Castiel's Garrison are murdered, and Lilith is immediately suspected.

Castiel and Uriel have Dean, Alastair's former apprentice during his time in Hell, torture Alastair to learn how Lilith is killing the Angels. Alastair, however, breaks free, beats up Dean, and almost exorcises Castiel when Sam appears and - after learning form Alastair that Lilith is not behind the deaths of the Angels - kills Alastair with his special powers. Castiel later discovers that his friend Uriel is the true culprit as well as an agent of Lucifer. Uriel tries to convince Castiel to help him free Lucifer, but Castiel refuses and fights his old friend. Though Uriel gets the upper hand, Anna appears and stabs him with an Angel Blade, killing the traitor.



Some time after this, Castiel learns something important and tries to warn Dean, but is captured by the other angels and taken back to Heaven, where he is tortured back into obedience. It's later revealed by Zachariah, a Seraph and Castiel's direct superior, that Senior Management intend on allowing the 66 Seals to break, so that Lucifer can burst free, and have Michael in his true Vessel Dean, destroy him, and cause everlasting paradise on Earth. It's also revealed that God has left Heaven, leaving the Archangels in charge to do whatever they wish.

Season 5


As planned, Lilith is killed (the Last Seal) by Sam, and Lucifer is freed. But Dean says no to Michael, which impairs "the final charge", making Lucifer unstoppable for the remainder of Season 5. Throughout the season, Zachariah tries repeatedly to get Dean to say yes, but Dean continues to refuse and eventually kills Zachariah himself. Anna Milton attempts stop the Apocalypse on her own by going back in time and killing John and Mary Winchester to prevent Sam's birth. She fails, however, and is killed by Michael. Gabriel resurfaces and tries to help the Winchesters kill Lucifer, but is killed himself. Throughout the season, Castiel, now a Fallen Angel with limited power works with the Winchesters to stop the Apocalypse.

Finally in Swan Song, Michael - in the vessel of the Sam and Dean's half-brother Adam Milligan - confronts Lucifer, Archangel to Archangel. Sam, who is serving as Lucifer's vessel, regains control of his body and throws both himself and Michael into Lucifer's Cage, ending the Apocalypse. Castiel, though killed by Lucifer during the final confrontation, is resurrected by God again as an even more powerful angel and he resurrects Bobby Singer, heals Dean and heads back to Heaven to restore order as the new leader.

Season 6


In the aftermath of Michael's imprisonment and God's abandonment of Heaven, the angels fall into disarray. They don't know what to do or who to take orders from. Castiel, who had rebelled against Heaven in order to help the Winchesters, returns to Heaven and starts preaching the idea of Free Will to his fellow Angels. However, many of the Angels can't even grasp the concept. The remaining Archangel Raphael confronts Castiel and demands that he kneel and repent for his rebellion. Raphael also plans to release Michael and Lucifer from the Cage, thus restarting the Apocalypse. When Castiel refuses to go along with this, Raphael threatens to destroy him and his followers unless they submit.

Castiel reluctantly makes a pact with the new King of Hell Crowley. Crowley and Castiel go to Hell, which Crowley personally re-designed, and there they plot to open Purgatory and absorb the souls of all the deceased monsters inside. Crowley gives Castiel 50,000 souls, which he uses to initiate a war against Raphael. Castiel also pulls Sam out of Lucifer's Cage, but accidentally forgets his soul. Despite gaining control of Heaven's Weapons, which the Angel Balthazar had stolen from the vault, Castiel's war goes badly, and he becomes more and more desperate to find Purgatory. When the Winchesters discover what he's been doing, they confront him, and he tries to convince them that he has to do this. When they refuse to back down, Castiel breaks Sam's 'wall', allowing his horrific memories of Hell to flood his mind.

Later, Castiel goes back on his deal with Crowley, and after opening Purgatory successfully, takes in all of Purgatory's souls. Unknown to him, he also absorbs the Leviathan. Castiel, utilizing/channeling the souls power (known among fans as "Godstiel"), obliterates Raphael.

Season 7
Castiel then goes to Heaven, and smites every surviving angel who ever helped Raphael. He informs the remaining angels that he is their father now, and that they must be obedient children or suffer the consequences. He then returns to Earth to begin destroying everything he perceives to be evil. Eventually, realizing the error of his ways, he goes to the Winchesters and Bobby for help. He says that if he were strong enough, he'd "fix" Sam. With their aid, he manages to send the souls back to Purgatory, but the Leviathan remain.

The Leviathan take over his vessel and him, and beat up Dean and Bobby. Then, they leave, and disperse into the water supply, leaving Castiel and his vessel seemingly destroyed. However, he is resurrected yet again, and Castiel awakens without any memory of who or what he is. He goes by the name "Emanuel" and marries the human woman who found him. Dean and Meg are able to remind him of who and what he is, and he, upon re-gaining his memory, tries to save Sam - who's been driven to near insanity by hallucinations of Lucifer - but realizes that the 'wall' has completely crumbled. He then shifts Sam's "pain" (condition) unto himself. While this cures Sam, Castiel is forced to stay at the mental hospital under the protection of Meg.



Meanwhile back in Heaven, the angels Hester and Inias have taken command of the few angels remaining. When Dean and Sam break the "shell" of The Word of God reputedly, a ting is emitted, one that only Angels can hear. When Castiel hears it, he awakens, only differently; more timid, calm, and refused to fight. At the same time, Hester and Inias go to Earth to retrieve both the Word and the Prophet Kevin Tran - who has been chosen to be the Keeper of the Word. However, the Winchesters need Kevin to the stop the Leviathan and a conflict ensues between the Winchesters and the Angels. The dispute ends when Meg steps in and kills Hester, after which Inias takes charge and agrees to stand down.

Castiel provides Dean and Sam with his blood for the weapon then goes off on his own. When looking for flowers and fruit (flowers come first obviously) he can't hear anything from his garrison. After a long silence, he goes to the home of the Prophet Kevin Tran and finds the entire Garrison dead or in hiding - victims of the Leviathan.

Upon Dean's request, Castiel teleports himself and Dean to the Impala, and he ultimately decides to take part in the fight. Together, the two of them sneak into SucroCorp's lab, where they find Dick Roman and another Leviathan Royce testing a batch of poisoned creamers. Cas douses Royce with Borax as Dean beheads him. He then distracts Dick Roman long enough for Dean to stab him with Bone Of Righteous Mortal Washed In the Three Bloods of Fallen, killing the Leviathan leader, though he and Dean are transported to Purgatory in the process.

Season 8
A repercussion of stabbing Dick with the Anti-Leviathan weapon, both Dean and Castiel are pulled into Purgatory. Heaven's Angels are terribly reduced, leaving an unknown amount of Angels. An observer and admirer of Castiel, Samandriel, takes a vessel, and contributes in the auctioning of one of the Words of God.

A new group of angels, led by Naomi, rescued Castiel from purgatory. They are keen on keeping track of developments involving the tablets containing the Words of God.

Characteristics
"Perfect... Like a marble statue. Cold... no choice... only obedience."

- Anna, about being an Angel



As warriors of God, Angels are extremely powerful beings in the supernatural world. Their true spiritual forms or visages prove overwhelming to most mortals, however, some special people can view their true visages without suffering lasting effects; demons also can't look at them in their true form without damaging their host. A key example of this: Pamela Barnes used her psychic powers to see the true form of Castiel and her eyes burned out as a result of her actions. Although not physically seen, an angel's true form has been seen as a brilliant white light; respectively, angels do have swanlike wings. In "Lazarus Rising", Castiel displays his wings through his shadow. When Angels die after being stabbed by an angelic blade, shadows of their wings (Angel's wings) are burned into the surface on which they are lying, as seen in the opening of "On the Head of a Pin" when Castiel finds a female angel dead on a street, and again when Anna kills Uriel and when Zachariah and Gabriel were killed. Also, in "Dark Side of the Moon", Zachariah tells Dean and Sam that in his true form he has six wings and four faces, one of them being that of a lion. It's possible that the number of wings an angel possess represents their rank or power since Castiel was shown to have two wings, while Zachariah, his superior, has six. Angels' true forms also appear to be very large, as evidenced when Castiel states that his true form is "about the size of your Chrysler building".

Anna Milton describes angels as being emotionless, not permitted to have feelings or free will. She even goes on to compare angels to marble statues, in the sense that they're both cold, loyal and have no choice. Despite being an angel herself, this description that Anna gave to Dean has been proven wrong on many occasions. Castiel has shown loyalty to the Winchester brothers and regret when he was ordered to kill Anna. Gabriel has shown anger and love towards his brothers, Michael and Lucifer, in "Changing Channels". In "Dark Side of the Moon", Zachariah shows signs of anger and pride. In "My Bloody Valentine", Cupids are shown to be very cheerful, emotional, and love giving hugs. To be more accurate, angels are very much capable of human emotions, rather the majority of them choose not to show emotion as emotions are considered doorways to doubt as well as a weakness, and they are not permitted to display emotions for the same reasons.

Angels consider themselves family to one another, referring to each other as brothers and sisters. The angels also refer to God as their father. Even though God is their father, all angels except the Archangels have never actually seen God or his true face. According to Anna Milton, only four angels have actually met God and seen his true face. These four are thought to be the Archangels. However, by a comment made by Joshua, it is probable that both he and Zachariah have met God personally.

Unlike humans, angels do not reproduce. Anna tells Dean that one of the things that humans have that angels don't is sex. Dean even describes angels as "Ken dolls" meaning that the only way for them to have sex is to possess a human.

Due to their age, and power, many angels look down upon humans and see them as inferior. Lucifer rebelled because God loved humans more than Angels. Some angels continued to hold resentment to this many thousands of years later, as evidenced by Uriel and his followers. Despite this, angels guard the souls in Heaven, and as shown in "What's Up, Tiger Mommy?" refuse to pawn them, even for the Word of God. Feelings of resentment aren't universal, as some angels such as Samandriel and Inias are much more civil with humans, while others such as Anna and Gabriel consider them better than angels.

The episode "Torn and Frayed" has shown that after a sufficient amount of torture, angels came be broken and their "operating system" be accessed. Angels have secret knowledge pre-programmed into their being that they aren't even aware of. The screams an angels makes when tortured sends out ripples that cause strange occurrences, such a bush lighting on fire.

Archangels - High-tier powers


The five eldest and most powerful of God's angels. Four of them at the most were the only ones to have seen his face. They exist on a higher plane of existence, being imbued with unimaginable and unmeasurable power and authority. Furthermore, they are some of the strongest beings in all of Creation. The first four archangels that were revealed were born in this specific order: Michael, Lucifer, Raphael, Gabriel, and it's ambiguous as to when Metatron was born. They are apparently the only known angels to have met God personally, and therefore believed to have been the angels Anna described. There are at least only two archangels alive now; Michael and Lucifer (both are currently sealed in Lucifer's Cage), as Gabriel was killed by Lucifer, and Castiel killed Raphael when the former was imbued with power from Purgatory's souls, and Metatron's status is unknown.

Metatron, the scribe of God, was mentioned to be an archangel. However, he is yet to make an appearance. His age and status relative to the other four archangels is also not yet stated.

Seraphim - Mid-Tier powers


The Seraphim (Zachariah was for a long time the only known Seraph) are a whole another type of Angelic being, who ranks higher than angels and Cupids. Zachariah, for example, was Castiel's direct superior, before his demise. Castiel, after all his resurrections, became a Seraph. The Seraphim report to the Archangels. They can be killed by regular Angel blades, but for some reason, they don't tend to carry their own blades. Castiel (after being promoted) and Zachariah are the only known Seraphim. Like the Archangels, their powers are imbued within them and if they Fall or become cut off from Heaven, they don't lose any of their powers.

Angels - Low-Tier powers


These are normal, common angels. Though not nearly as powerful as the Archangels or Seraphim, they can still destroy demons and Earthly monsters with relative ease. They are grouped into garrisons and are commanded by the Seraphim. They often carry Angel Blades. It is said that none of them have actually ever met God, and thus must rely on faith and obedience.

Cupids


Cupids, also called Cherubim in the celestial chain or sphere, are ordered as third class angels, and thus placed at the very bottom of the Celestial chain of command, Heaven's hierarchy. They follow Heaven's orders, particularly serving Michael. In their occupation, they are responsible for manipulating affection in certain, special bloodlines. John and Mary Winchester, for example, were "matched" by a Cupid (however, not the one who appeared in "My Bloody Valentine") on Heaven's orders so that Dean and Sam could be born.

Fallen Angels
Fallen Angels are angels who either were banished from Heaven, or who voluntarily left. They look no different than normal angels (as they're not another race of angel), but sometimes affects their abilities, depending on the rank of angel. However, a Fallen Angel's blood can potentially be used in the Anti-Leviathan killing weapon. Known banished angels include Lucifer and Anna Milton who fell on their own accord. Castiel is the most recent Fallen Angel having fallen twice: once when rebelling against the Apocalypse and the second (and current time) when he left of his own accord. Since he's a Seraph he retains all of his powers and abilities.

Low-tier powers
Common powers granted to all angels with varying levels of effectiveness.
 * Angelic Possession - Similar to demons, angels require a vessel while on Earth. However, they must have the vessel's permission before they can take control.
 * Astral Projection - Angels can project their wings onto surfaces at will. If one is killed by an Angel Blade, its wings are burned onto the surface on which they died.
 * Chronokinesis - Angels can travel through time, in either direction. They can also take others with them, and just send others without going themselves. However, this is a very difficult ability to master with or without Heaven's assistance. More powerful angels such as Seraphs or Archangels are able to manipulate time easier, even when cut off from Heaven.
 * Dream Walking - Angels can appear in people's dreams, they usually use this to communicate, when they can't find the person they're looking for, or want to talk privately. Lucifer was able to talk to his future vessels in their dreams.
 * Eidetic Memory - Angels have the faces of every prophet who has existed or will exist etched into their memories. This ability also makes them aware of reality warping and timeline changes.
 * Electronic Manipulation - Angels can manipulate electrical appliances. Castiel caused a dozen car alarms to stop by snapping his fingers.
 * Immortality - Angels don't age and cannot be killed by diseases or Earthly weapons.
 * Invulnerability - To date, the only things capable of killing angels are Angel Blades, Holy Fire, a stronger angel, Death, God, and Leviathans. Archangels have even fewer weaknesses, as Michael wasn't killed by the  Holy Fire, and they can only be killed by Archangel Blades, not ordinary Angel Blades. It has been stated that Death's Scythe can kill angels.
 * Regeneration - If an angel's vessel is damaged, it will repair itself nearly instantly unless the wound was caused by angelic weaponry .
 * Sedation - Angels are able to render humans unconscious with a touch.
 * Super Stamina - Angels never tire, and they do not require food, water, oxygen, or sleep to sustain themselves.
 * Super Strength - Physically, regular angels are more than a match for humans, lower-level and mid-level demons, and most monsters. Higher angels like Seraphim can kill any demon. Archangels can overpower and kill any demon, creature, monster or pagan god. They can also kill all other angels with ease.
 * Supernatural Perception - Angels are able to see all supernatural activity around them. Castiel could even see Reapers, which remain invisible except to those they are seeking. They can also sense any location, being, or object not protected by Enochian Symbols. This perception also extends to electromagnetic waves, and can decipher radio modulation signals, as angels are "multidimensional waves" in their true form and can thus percieve such energies.
 * Telekinesis - Angels are able to telekinetically move beings and objects with their mind.
 * Telepathy - Angels can read the minds of other angels with ease, higher angels such as Seraphs and Archangels can also read humans minds.
 * Teleportation - Angels are able to travel from one place to another, instantly, without occupying the space in between. They can also summon or send other beings.
 * Voice Mimicry - Angels can perfectly mimic the voice of mortals.
 * Protective Charm - An angel can protect an individual (commonly their future vessels) from most forms of physical damage. This degree of protection is linked to an angel's power. Castiel was able to prevent his vessel Jimmy Novak from burning his hand on a pot of boiling water as a sign of faith. Raphael was capable of making Crowley immune to Castiel's angelic killing touch.
 * Flight - All angels are able to fly, though it's only been shown when not in a vessel. It may be linked to their teleportation due to the sound wings flapping when they teleport.
 * Pyrokinesis - Castiel displays the ability to burn through ropes holding him, even before it becomes a Seraph.
 * Invisibility - Some angels can become invisible to humans.

Powers accessed through connection to Heaven
To lower-level angels, certain powers are granted and maintained as long as stay connected and loyal to Heaven and it's rulers. Should they rebel and fall, those powers will wane and eventually vanish in time. However higher-level angels such as Seraphim and Archangels do not suffer from this condition.
 * Enhanced Chronokinesis - The ability to bend time is easier if the angel is connected to Heaven.
 * Healing- Angels can cause the wounds, diseases, and toxins of another being to heal instantaneously.
 * Killing Touch - Angels are able to destroy lower-level demons with a simple touch, however the demon has to be in a host body, as this doesn't work on their smoke form. They can also use it to kill monsters and humans. More powerful angels, like Raphael, are proficient enough to scare (and kill) a demon as powerful as Lilith.
 * Resurrection - Angels can bring the dead back to life. However, they must know where all the pieces of the original body are, and they must have the soul of the subject. (The only known exception was when Castiel went to Lucifer's cage and only was able to raise Sam's body. His soul remained in the cage for over a year after). Castiel mentions that angels had to lay siege to Hell in order to retrieve Dean.

Mid-tier powers
Abilities more commonly used by higher classes of angels such as Seraphim and Archangels.
 * Biokinesis - Higher level angels, such as Seraphim, like Zachariah, are able to manipulate the biology of other beings. Zachariah, for example, was able to make Dean hemorrhage while torturing him into saying yes to Michael.
 * Vessel Locking Advanced - Powerful angels can hold a demon in smoke form as if it was tangible and force the demon to return to its vessel. This was demonstrated by Castiel on Ellsworth.
 * Memory Manipulation - Powerful angels are able to erase, restore, alter, and fabricate memories in the minds of humans.
 * Advanced Pyrokinesis - Powerful angels can generate and manipulate fire. Michael was proficient enough to kill another angel, Anna, by setting her ablaze from within. Interestingly, this didn't simply destroy the vessel, it also killed the angel, suggesting the fire had a supernatural element to it.
 * Soul Reading - Angels are able to read the souls of humans, however it is a painful experience for the human. They can also use the soul as a source of energy, but the pain is even greater for the human, and there is the risk of an explosion if the angel is not careful.
 * Reality Warping - Powerful angels can bend reality to their will. The most notable example is Gabriel, who lived on Earth as masquerading as a Trickster named Loki. Mid-level angels, can only do much easier things, such as breaking and repair objects by pointing, or assembling a game by shaking the box.
 * Power Removal - Powerful angels such as Seraphs are capable of removing psychic powers from human beings. However, the process is very painful and can leave the person mentally-damaged.

High-tier powers
Extremely powerful abilities, used only by Heaven's most powerful denizens, the Archangels.
 * Cosmic Awareness - All archangels have a superhuman knowledge of the universe.
 * Cryokinesis - Lucifer demonstrated the ability to freeze a pane of glass with his breath. His presence can cause an entire town to drop in temperature.
 * Electrokinesis - Raphael could produce powerful arcs of electricity that appeared from his back.
 * Holy Light - Archangels are able to use that power can kill or injure almost everything. They can also control the intensity of the this power.
 * Hydrokinesis - Archangels can manipulate water.
 * Molecular Combustion - Lucifer caused Castiel to explode by snapping his fingers.
 * Shapeshifting - Lucifer was able to take multiple forms while not in a vessel, and while in vessel, Gabriel could also do this.
 * Weather Manipulation - Raphael was able to generate storms that caused blackouts over the entire Eastern Seaboard. Lucifer unleashed incredibly fierce winds with his release.
 * Terrakinesis - Able to create servear quakes simply by willing it

Other

 * Matchmaking - Certain types of angels in the Cherub class, e.g. Cupids, can bring couples together by marking their hearts.
 * Materialization of the body - Despite being of the absolute lowest hierarchy, Cupids, unlike any other Angel (Archangels, Seraphs, and Angels), are able to materialize a body without a ship unlike the other angels.

Weaknesses
Angels are difficult to kill. The methods that are used to hurt or kill demons and humans will not affect them at all. In On the Head of a Pin, Uriel states that the only thing that can kill an angel is another angel, though this has been shown not to be the case as both Dean and Meg have killed angels before. Although there are not many ways known, there are methods to stop or kill an angel. Archangels are next to impossible to kill.

Harming, Misleading and Trapping

 * Holy Fire - Encased in flames created from Holy Oil, the angel is trapped. The trapped angel still can use their powers, possibly aiding them to escape. Touching the flame will kill the vessel and the angel. However, it cannot kill Michael, being only able to banish him.
 * Lucifer's Cage - Strong enough to securely contain normal angels and Archangels; it is currently holding the two strongest Archangels in existence, Michael and Lucifer.
 * Enochian Sigils - When Enochian sigils are placed on human rib cages, they prevent any angel/archangel from detecting and finding them. They can also be used to prevent angels from entering a building by painting them on the building's walls. In Torn and Frayed, the sigils on the walls dramatically weakened Castiel's powers..
 * Hex Bags - Hex bags can used to prevent angels from detecting and finding someone (these cannot hide someone from Archangels in vessels).
 * Higher Demons / Large numbers of Demons- The highest Demons, Alistair, Lilith and (presumably) Azazel are able to fight, overpower, harm, and even banish lower level Angels, they can't kill them though. Significant numbers of demons can also overpower angels as Crowley's army of demons was able to defeat Castiels guards ("The Man Who Knew Too Much")

Banishing or destroying

 * Blood Seal - If a person places his or her hand upon this blood seal that is placed upon something then all angels in the immediate area will be banished away. An angel can activate this seal as well. If an angel activates the seal then the angel who activates the seal will not be banished along with the other angels in the area. The blood seal can also be place upon a person's body. If an angel activates the seal this way (carved into its vessel's chest), he or she will be banished along with the other angels.
 * Exorcism Chant - There is an exorcism chant to expel angels from their human vessels and send them back to heaven. It seems that the chant is not well known as the only entity to use it was Alastair.
 * Angelic Blade - An angel can be killed by stabbing him or her with an angelic blade. It seems that the angel must be stabbed in a vital area of the human body, such as the head, heart, neck, or stomach. When an angel is stabbed by an angelic blade, a burst of bright, white light is released and angel wings are burned on the surface underneath the body of the angel's human vessel.
 * Archangel Blade - Archangels seem to have their own angelic blades that are probably more powerful than normal angelic blades. It seems that a Archangel blade is capable of killing both normal angels and Archangels as shown when Lucifer killed Gabriel with his own blade.
 * Weapons of Heaven - Harms angels and archangels; so far it has been shown that a weapon of Heaven can destroy an archangel's human vessel so that it can not be resurrected as seen with Donnie Finnerman, the true vessel of Raphael.
 * Colt (Possibly) - Castiel believed that the Colt was the only thing that could possibly kill Lucifer. Although, a shot to the head failed to kill Lucifer, it's unknown if the Colt is capable of killing other archangels, although this is highly unlikey.
 * Death's Scythe - Although it has not been seen in action, this item is said to have the power to reap any living being, whether it be human, demon, angel, and its rumored to even be able to reap Death himself.
 * Leviathans - Leviathans can easily kill regular angels, as demonstrated at the end of the episode "Reading Is Fundamental" when Edgar kills Kevin's two angel escorts by sticking his fist into their chests and injecting them with black Leviathan blood. According to Castiel, one of the reasons why God locked the Leviathans up in Purgatory was because they could kill angels. They can also over-power and kill Seraphs. It is unknown if they can kill or challenge Archangels or vice versa.
 * Hellhounds (possibly) - Hellhounds might be able to harm or kill Angels as upon there approach Castiel ran along with Dean, Sam, Meg and two other Demons.

Other

 * Eve - a being older than the angels themselves, can suppress their powers through her mere presence alone.

Cherubim

 * Cupid

Angels

 * Castiel (promoted)
 * Uriel
 * Anna Milton
 * Joshua
 * Balthazar
 * Virgil
 * Rachel
 * Hester
 * Inias
 * Samandriel
 * Naomi 

Seraphim

 * Zachariah
 * Castiel

Archangels

 * Michael
 * Lucifer
 * Raphael
 * Gabriel
 * Metatron (Mentioned only)

Season 2

 * Tall Tales (Gabriel, disguised as The Trickster) - first appearance of an Archangel

Season 3

 * Mystery Spot (Gabriel, disguised as The Trickster)

Season 4

 * Lazarus Rising (Castiel)
 * Are You There, God? It's Me, Dean Winchester (Castiel)
 * In The Beginning (Castiel)
 * It's the Great Pumpkin, Sam Winchester
 * I Know What You Did Last Summer
 * Heaven and Hell
 * Death Takes A Holiday
 * On The Head Of A Pin
 * It's A Terrible Life (Zachariah) - first appearance of a Seraph
 * The Monster at the End of This Book - first named semi apperance of an Archangel
 * The Rapture
 * When The Levee Breaks
 * Lucifer Rising

Season 5

 * Sympathy for the Devil - first named proper apperance of an Archangel
 * Good God, Y'all (Castiel)
 * Free To Be You and Me
 * The End
 * I Believe The Children Are Our Future (Castiel)
 * Changing Channels
 * Abandon All Hope...
 * The Song Remains the Same
 * My Bloody Valentine - first apperance of a Cherub
 * Dark Side of the Moon
 * 99 Problems (Castiel)
 * Point of No Return
 * Two Minutes to Midnight (Castiel)
 * Swan Song

Season 6

 * The Third Man
 * You Can't Handle The Truth
 * Family Matters
 * Caged Heat
 * Appointment In Samarra
 * Like A Virgin
 * The French Mistake
 * My Heart Will Go On
 * Frontierland
 * Mommy Dearest
 * The Man Who Would Be King
 * Let It Bleed
 * The Man Who Knew Too Much

Season 7

 * Meet The New Boss
 * Hello, Cruel World (Castiel)
 * The Born-Again Identity (Castiel)
 * Reading Is Fundamental
 * Survival of the Fittest (Castiel)

Season 8

 * What's Up, Tiger Mommy?
 * Blood Brother
 * A Little Slice of Kevin
 * Hunteri Heroici
 * Torn and Frayed