Naomi

"When I learned of the Angel Tablet, I did tell Castiel to get it at any cost. That's my job--to protect Heaven. I'm a warrior, just as you are."

- Naomi to Dean

Naomi was a high-ranking angel charged with making rebellious angels obedient once more and extracting information from them. Following the slaughter of Raphael's followers at Castiel's hand, Naomi headed one of the many factions of angels vying for leadership of Heaven. She saved Castiel from Purgatory to brainwash him into being her unwitting agent in Season 8. Upon learning of Metatron's plan, she attempted to stop the scribe, only to be killed by him instead.

Background
From her dialogue, it appeared Naomi had been an important player in Heaven for thousands of years. She mentioned wiping Castiel's memory so many times, he forgot events of his past, such as the massacre of firstborns in Egypt over three thousand years ago. It was revealed that she worked directly under the archangels, and was supposed to "debrief" Metatron, following God's departing, but he fled before she was able to. Her team alone knew of the operations that modify memories of lower-class angels.

A Little Slice of Kevin
After Castiel confronted Crowley, she whisked Castiel to Heaven. She told Castiel she was responsible for saving him from Purgatory. Naomi asked Castiel to tell her information about the Winchesters, which Castiel did casually and without hesitation, much to his own surprise. Naomi then urged Castiel to help the Winchesters recover the tablet. Before she sent Castiel back to Earth, Naomi made it clear she wanted Castiel to report to her every now and then. She also promised that no one would even know when and if he reports to her. Castiel disagreed, but Naomi disregarded his resistance and merely smiled. True to her word, when she sent him back, he was unable to remember he had spoken to her.

Hunteri Heroici
Near the summation of the episode, she yanked Castiel to Heaven, and had a brief word with him. She told him she did not want him in Heaven unless she permits it, prompting Castiel to question what he should do, after which she returned the question to him.

Torn and Frayed
When Samandriel inadvertently revealed the existence of a tablet pertaining to angels, she ordered Castiel to assassinate the captured angel. Naomi was convinced it had to be done to protect the angels and Heaven. She also wanted Castiel to bring Samandriel's remains to Heaven so she could examine how much information Crowley had extracted from Samandriel.

Goodbye Stranger
Naomi worked to indoctrinate Castiel to her control completely by having him kill hundreds of copies of Dean. After ruthlessly and successfully passing her test, Castiel was after the angel tablet. Naomi had Castiel lie that he was searching for the second half of the demon tablet when the Winchesters caught up to him during his mission. Castiel also killed a demon before the demon could tell them the truth. Naomi allowed Castiel to keep Meg alive as the demon knew the location of the angel tablet, but ordered the seraph to kill Dean after they locate the tablet. She explained to the powerless Castiel that he was "broken" and she "fixed" him when he is unable to stop himself from attacking Dean and told him to choose between Heaven and the Winchesters. Castiel managed to stop himself from killing Dean and when he picked up the angel tablet, it broke her connection and control over him. After Castiel left to protect the tablet from everyone including himself and Dean, Naomi visited the crypt where it had been located and met up with Crowley who showed familiarity with her and indicated a possible sexual relationship between them in the past. Though she was not happy, Naomi admitted that Castiel is doing what he was meant to do: protect the tablet even though it apparently meant protecting it from her as well. Crowley began to offer a deal, but an uninterested Naomi left even before the demon could lay out the terms. Naomi is later seen receiving a report that the angels had had no luck finding Castiel.

Taxi Driver
Naomi approached Dean to try to convince him that she is on his side. Naomi claimed that she periodically met with Castiel, but was not intentionally spying on the Winchesters and that Castiel misinterpreted her orders when he tried to kill Dean. Dean did not trust her, but Naomi informed him that Sam traveled to Hell through Purgatory before disappearing. Later, when Sam tries to release Bobby Singer's soul into Heaven and Crowley stops it, Naomi intervened. Though Crowley warns her the Winchesters will likely lock up Heaven too, Naomi simply told him she hopes he gets locked up and that she will figure out the rest. The annoyed demon labelled her a 'bureaucrat', prompting Naomi to smite him out of spite. Crowley fled and Naomi released Bobby, allowing him to go to Heaven where he belonged. Naomi reaffirmed to Sam and Dean that she wants what they do, Hell closed and then disappeared.

The Great Escapist
Naomi received word from Ion that they are unable to track Castiel through Biggerson's, so she had him slaughter all the people in one of the locations to draw Castiel out. Once he was captured, she ruthlessly killed a woman and interrogated Castiel for the location of the angel tablet, in turn revealing that he took part in the slaughter of firstborns in Egypt by angels and that she erased his memory of it. She revealed has erased his and other angels memories many times, but Castiel was different, as he never truly followed orders as he was supposed to. Crowley arrived and wounds Ion with a bullet made from an Angel Blade and kills the other angel with her. Crowley and Naomi had a stand-off, in which the angel fled after being shot at by the demon.

Clip Show
Metatron revealed that despite what Naomi claimed, she was not the sole ruler of Heaven, and that she was simply the leader of one of many factions of angels at civil war.

Sacrifice
Naomi learned Castiel had teamed up with Metatron. She came to the bar where the two were talking, and took Metatron away. Back in her office in Heaven, Naomi argued with Metatron, then she started to extract information from Metatron's head. She then learned Metatron's true intentions. She teleported to Castiel and told him Metatron was trying to expel them all from Heaven because he wanted revenge. She had come to realize that she was wrong, telling Castiel and Dean that angels were meant to protect God's creation and somewhere they lost sight of their purpose. She warned Dean that if Sam completed the trials, he will die and before leaving, she promised Castiel that if he truly wished to return to Heaven, she will hear him out. Naomi went back to Heaven where Metatron killed her by stabbing her in the head with her memory drill. Metatron later confirmed to Castiel that she was telling the truth.

I Think I'm Gonna Like It Here
Dean (unaware of Naomi's death) was quick to label her and Metatron as the people to blame for Sam's condition and the Angel's falling.

I'm No Angel
With Naomi's death an angel named Bartholomew, said to be the protégé of Naomi, took charge of the scattered Angels. When Sam and Dean were interrogating the rogue reaper Maurice, the reaper finally revealed to them that Naomi was dead and Bartholomew had taken charge.

Personality
Naomi appeared civil and normally friendly, and was willing to be diplomatic when it suited her. She also made effort to try and create alliances. However, she was also incredibly ruthless, and was more than willing to murder, torture, kidnap and brainwash others.

She valued order and discipline, and worked hard to preserve these qualities. She held angels somewhat highly, and worked for their benefits, but that would not stop her killing them if she felt there was the need. When it came to humans, Naomi was less caring and was willing to savagely murder and torture dozens of them simply to further her goals. However, she was also willing to be civil with them, especially if it benefited her. Like many angels, she hated demons and looked down upon them, although Crowley seemed to imply they had a relationship some thousand years ago. Despite this, Naomi still would not strike a deal with the demon. She longed for the gates of Hell to be closed, to the point where she helped the Winchesters to finish the second trial and insisted they could trust her because of that. However, after her change of heart, she revealed that closing the gates would kill Sam, even though she knew it would cause Dean to stop the trials, indicating that with her change of heart she became more compassionate and she developed the desire to prevent others from being sacrificed when there was another way.

Naomi was highly deceptive, and commonly kept others in the dark, often lying to and manipulating them. This deception would, in the end, prove to backfire on her, because Castiel would not believe her when she told him the truth about Metatron and his plans, leading to the Scribe succeeding in getting his revenge.

At the end of her life, Naomi showed remorse for her actions and actually cried, something no other angel has ever been shown to do. She also displayed anger, resentment and pride at times, showing that despite her disdain for humans, she possessed human emotions, something few angels ever display. One issue she was particually touchy about being dismissed as simply a "bureaucrat" and she made clear she saw herself much like most other angels as a "Warrior."

Powers & Abilities
While her exact rank in the Heavenly Host is unknown, Naomi was an undeniably powerful angel with a high degree of authority over Heaven and its denizens. She was capable of easily smiting Crowley and could over power even the Seraph, Castiel, thus she was one of the stronger angels in the series. She possessed all of the basic powers and weaknesses of an angel. Because of her power and high authority of Heaven and as a high ranking angel, Naomi could have possibly been a Seraph.
 * Compulsion - Naomi could compel other angels to follow her command. During their conversations, Castiel replied immediately and in full to any question she put to him. She later forced Castiel to murder Samandriel, an order he was unable to refuse. She lost this control over him however after their connection was severed by the angel tablet.
 * Immortality - As an angel, Naomi had the potential to live forever, even while in a vessel. She had been alive since at least Moses was in Egypt, making her well over 3,000 years old.
 * Invulnerability - As an angel, Naomi could not be killed by convential methods, but she was still vulnerable to angel blades.
 * Memory Manipulation - When Castiel was returned to Earth, he was unable to remember speaking with her. It was later revealed that Naomi had erased Castiel's memory multiple times over the several millenia due to the Seraph's constant refusal to follow through with his given commands.
 * Apporting - Naomi was able to transport Castiel from Earth to Heaven and then teleport him back to the exact place and time without the Winchesters noticing. She could also prevent Castiel from re-entering Heaven again without her consent. She had also shown the ability to converse with Castiel in Heaven while Castiel himself was also present on Earth. She lost this control over him however after their connection was severed.
 * Super Strength - As a high ranking angel, Naomi was much stronger than humans, spirits, monsters, demons, and most angels. She could easily lift Castiel, a Seraph, off his feet and was able to restain the Angel Scribe of God Metatron with one hand as an angel blade was in her other hand.
 * Angelic Possession - As an angel, Naomi was able to possess a human to walk on Earth. She of course needs the vessel's consent.
 * Teleportation - Being an angel, Naomi was able to instantly teleport from one place to another.
 * Holy White Light - Similar to the archangels, Naomi was able to emit a blast of light from the palm of her hand. During a confrontation with Crowley, Naomi tried to blast him with the light, but he fled before she could.
 * Spell Negation - Naomi was able to neutralize Crowley's spell to capture Bobby's soul with a simple hand movement.
 * Telekinesis - Naomi could move objects with her mind. With a simple finger movement, she snapped a waitress's neck and pulled a chair to her by snapping her fingers.

Appearances

 * Season 8
 * A Little Slice of Kevin
 * Hunteri Heroici
 * Torn and Frayed 
 * Goodbye Stranger 
 * Taxi Driver
 * The Great Escapist
 * Sacrifice
 * Season 9
 * I Think I'm Gonna Like It Here  (Mentioned only)
 * I'm No Angel  (Mentioned only)

Trivia

 * Before Season 8 began, Naomi was described in press releases as being part of a group of angels never seen before. Ion indicated that this group was an intelligence division of Heaven when talking to Castiel. Naomi also indicated this when she mentioned how she had to "debrief" Metatron after God left.
 * The name "Naomi" translates into "pleasant" or "my sweet" in Hebrew and "beautiful honesty" in Japanese; this is ironic considering the character's role as a major antagonist who frequently deceives others.