Belphegor

"Look, I-I'm not some Crossroad Demon. I'm not even one of those black-eyed goons who crawled his way up here to eat, you know virgins and puppies and, uh, virgin puppies. Look, Downstairs I punch a clock. A soul comes in, I torment it, it's what I do. (...) The point is, I like my job. I like Hell the way it is -- or -- or was. So, all those bad guys? You want them back where they came from, right? Well, me too."

- Belphegor introducing himself to the Winchesters and Castiel.

Belphegor was a demon who worked as a torturer in Hell, and was released to Earth when God attempted to end the world by releasing every soul from Hell. Though he initially presented himself as an ally to the Winchesters and Castiel, he later betrayed them in an attempt to absorb all the souls from Hell, intending to become it's new ruler. This plan was quickly thwarted by Castiel.

Background
Like all demons, Belphegor was once a human.

He presumably died and went to Hell thousands of years ago, as he told Dean that when he was alive, his people worshippped a "giant rock that looked like a penis."

During his time in Hell, Belphegor became a torturer of souls. When Dean was condemned to Hell in 2008, Belphegor witnessed and become a fan of Dean's torturing skills. According to Ardat, Belphegor conspired to become the King of Hell for centuries, closely following Lilith and Crowley in an attempt to rise in the ranks.

When God breaks Hell open, allowing all of the souls to escape, Belphegor uses the opportunity to leave Hell for the first time since he died as a human.

Season 15
In Back and to the Future, after escaping from Hell, Belphegor possesses Jack Kline's corpse. At first, the Winchesters think that Jack has come back to life, but Castiel is able to tell that it's actually a demon using Jack as a vessel. Belphegor explains that he just arrived and needed a body, commenting that he would show them his eyes if Jack's weren't burned out. Putting on a pair of sunglasses to blend in, Belphegor introduces himself and ignores Castiel's orders to get out of Jack's body. Castiel pins Belphegor to a wall and demands that he get out of Jack with an angel blade to his throat, but Belphegor insists that he can help. Castiel continues to threaten Belphegor, calling him an abomination, causing Belphegor to mock Castiel's trench coat. Dean finally pulls Castiel off of the demon so they can hear him out as they need the help. Castiel is angry as Belphegor is defiling Jack's corpse, but Dean states that Jack's gone and if Belphegor can help they should let him which Sam agrees to.

Sam tries to introduce them to Belphegor who reveals that he already knows who they are as he reads the papers. Belphegor guesses the whole hellmouth thing is them and is shocked when Sam and Castiel explains that it was actually God. Belphegor explains his role in Hell and that he likes his job and his role in Hell as it was. As a result, he also wants all of the souls back in Hell. Belphegor admits that he can't fix the whole situation, but he can get them out of their current danger. Gathering graveyard dirt and Castiel's blood, Belphegor slaps his hands together and casts a spell that causes the zombies to stop. Emerging from the crypt, the group finds the zombies lifeless on the ground and Belphegor explains that he simply blasted the souls out of their bodies, leaving Dean wondering where the ghosts are.

Belphegor joins the Winchesters and Castiel in the Impala, admiring his vessel in the mirror and commenting "for now" when Dean thinks they are only dealing with a ghostpocalypse confined to the one area. Belphegor points out that all of the souls have to go somewhere and when Sam asks how many souls they are dealing with, Belphegor states that there are two to three billion souls in Hell. Dean states that they should go back to the Men of Letters bunker and find a way to close the rift unless Belphegor has a better plan. Although he admits that he doesn't have a better plan, Belphegor suggests that they buy some time by containing the ghosts with a spell that will create a barrier a mile wide which no ghosts can enter or leave. Castiel realizes that Harlan, Kansas is less than a mile from the cemetery and thus within range of the barrier. As a result, Dean suggests that they evacuate the town by lying. After the Winchesters spot a car by the side of the road covered in blood, Belphegor remains in the car with Castiel while they investigate.

The next morning, as Sam begins the evacuation of the town, Dean orders Castiel to help Belphegor to get the ingredients for the spell while the Winchesters handle the evacuation. Castiel, unable to even look at Belphegor, instead leaves to help Sam with the evacuation while Dean helps with the spell. Dean ignores Belphegor's interest in the Equalizer and Belphegor expresses interest in the way people look in the present, commenting on how different people are now to when he was last on Earth when Belphegor was human, annoying Dean. Dean questions when Belphegor will get out of Jack's body and he promises to when he finds another vessel, commenting that he didn't take one at the cemetery as the bodies there were all too "wormy" for him and difficult to blend in. Dean admits that Jack was their kid "kind of," causing Belphegor to apologize. At Dean's prompting, Belphegor tells him that they will need a big bag of salt for the spell and a human heart.

When Dean returns with a bag of rock salt, Belphegor tells Dean that he is a fan of Dean, having witnessed Dean at work in Hell with Alastair which Dean brushes off as being a long time ago. Dean questions Belphegor on the current state of Hell and he explains that every door in Hell sprang open all at once, causing Dean to realize that this includes Lucifer's Cage. Concerned, Dean asks about Michael and Belphegor tells him that last he heard, Michael was just sitting in the Cage, but suggests that if Michael got out, he will want revenge.

Walking together, Belphegor brings up their need for a human heart for the spell and Dean states that he is planning to hit the local morgue. However, Belphegor states that they need a fresh heart. Investigating a scream, the two find the local sheriff dead and Belphegor rips out his heart to use in the spell. With Dean's breath becoming visible, he tells Belphegor they need to move before he is attacked by Constance Welch. With the ghost turning on him, Belphegor claims not to know Dean and tries to talk her down only to have Constance slash his hand open. Dean dissipates the ghost with an iron bar and orders Belphegor to perform the spell immediately. Placing the heart in a pile of salt, Belphegor casts the spell, trapping the ghosts within a one-mile radius of the cemetery and containing them for the time being.

After trapping the ghosts, the Winchesters, Castiel and Belphegor bring a mother and daughter Sam and Castiel rescued to the high school where the town's residents are gathering. Belphegor makes a sarcastic comment as the Winchesters tell the two residents not to tell anyone about the ghosts or angel as it might freak them out. Noticing the awkwardness of the situation with Dean and Castiel, Belphegor asks if Castiel wants to talk about it, but he just ignores the demon.

In Raising Hell, Dean and Belphegor walk the perimeter of the barrier using the demon's ability to see the ghosts even while they are invisible to prevent escape attempts. Belphegor notes that the spell won't last forever and they aren't dealing with normal ghosts. When Belphegor comments that he's not the ghosts' favorite, Dean asks if he was a dick to them in Hell. Belphegor insists that he just did his job and "it's Hell, not a day spa." The two note the irony of teaming up with a demon and a hunter respectively and Dean asks after Belphegor's motivations. Belphegor insists that he likes Hell the way it was and he's "a good soldier." Belphegor draws Dean's attention to a ghost trying to escape and identifies him as Francis Tumblety, aka Jack the Ripper.

Belphegor joins the Winchesters when Francis uses two possessed people to try to force them to drop the barrier before Arthur Ketch intervenes. Belphegor later gives an update on the situation to the Winchesters, Arthur and Rowena MacLeod. After learning who Belphegor is, Arthur reveals that he was hired to assassinate him, supposedly because Belphegor is "a monstrous threat to humanity." Arthur and Belphegor identify his employer as the demon Ardat who hates Belphegor. Sam tells Arthur not to kill him as they need the demon with Dean adding "for now."

As Sam and Dean patrol the perimeter, Belphegor appears behind them and they reveal that they have learned from a reliable source that the barrier is beginning to fail. Belphegor states that he figured they'd already know that and can't strengthen the barrier as it was a one-time thing. After learning that their source is Kevin Tran, Belphegor is annoyed, calling Kevin a "whiney millennial." Though Dean insists that Kevin belongs in Heaven, Belphegor reveals that souls cast down to Hell can't go to Heaven which can't take them. When the Winchesters point out that their father and Bobby Singer both made it to Heaven after escaping from Hell, Belphegor figures God made a couple of exceptions and without him on their side, there's nothing they can do about it.

Belphegor joins the Winchesters, Castiel and Rowena at the barrier's weakest point where the ghosts are massing to try to break through. Belphegor notes that at least a hundred are trying with more coming and points out the uselessness of Dean's attempts to stop the ghosts with rock salt. As Rowena uses the Soul Catcher to trap the ghosts, Belphegor announces that it is working, only for Arthur to be revealed to be possessed by Francis Tumblety. However, Dean shoots Francis with iron bullets, expelling him from Arthur and allowing Rowena to finish the job. Belphegor exchanges a nod of satisfaction with Dean.

After deciding to continue roaming the Earth as a ghost, Kevin requests that Belphegor open a door in the barrier for him to get out. Belphegor complies with Kevin's request, though he becomes annoyed at the length of time their goodbye takes. Rowena and Castiel then draw their attention to more ghosts rising out of Hell, alarming the group. Belphegor notes that soon the ghosts will overrun them again once the barrier falls. Additionally, Rowena's Soul Catcher isn't strong enough to handle all of the ghosts and they need to find another solution before it's too late. Though Sam is confident they will find one, Dean is left wondering how.

Personality
Belphegor displays a generally friendly and sarcastic demeanor, using the phrase "you know" a lot in conversation. He also appears to be somewhat pessimistic, stating that his spell only got the ghosts out of the bodies they were possessing for now and saying the same thing when the Winchesters comment that the ghostpocalypse appears to be confined to their immediate area. When Dean brings up finding a way to close the rift to Hell, he expresses pessimism on whether or not they actually can. His behavior tends to be obnoxious and annoying to those around him at times. Additionally, he appears to be somewhat impatient.

Despite his friendly demeanor, Belphegor has a sadistic side as shown by his enjoyment of torturing souls in Hell. He is a fan of Dean's, having seen Dean torturing souls in Hell with Alastair, calling Dean's work "art." When discovering a dead corpse, he smiles at it and rips out the dead man's heart to use it for a spell because he needed a fresh one. Due to his job, Belphegor is shown to generally be hated by the souls of Hell to the point that they will avoid him even after simply spotting the demon from the other side of a barrier. In return, Belphegor is shown to have a generally low opinion of the souls, calling Kevin Tran a "whiney millennial."

Belphegor appears to be something of a coward when faced with a situation out of his control. When threatened by Castiel, he replied with snark, but knew that the Winchesters and Castiel needed his help more than they wanted to kill him. However, when faced with the Woman in White of Constance Welch, Belphegor attempted to lie and talk his way out of trouble rather than defending himself in any way against the ghost.

Belphegor is later revealed to be lying and manipulating the Winchesters and Castiel in order to gain power in Hell. According to Ardat, Belphegor spent centuries "bowing and scraping" to the other Rulers of Hell such as Lilith and Crowley while waiting for his own chance to take power. While Belphegor puts on an outwardly friendly demeanor, he is in reality pure evil with Ardat suggesting that he may be particularly bad when she asks Castiel "don't you know what he is?" Ardat indicates that if Belphegor came to power in Hell, he would reshape it in a particularly terrible way. When attacked by Castiel, the first person to suspect his true nature, Belphegor tries to pretend to be a suddenly resurrected Jack as a last resort as he is no match for the Seraphim. However, Castiel easily sees through the lie which is rather transparent.

Powers and Abilities
Belphegor appears to be a regular demon with all the powers of one. However, he does have a great knowledge of magic and witchcraft, and is apparently an expert torturer, sufficiently to become a torturer of Hell. Despite his apparent age, he doesn't appear to be particularly powerful on his own.
 * Demonic Possession - As a demon, he requires a vessel to walk the Earth.
 * Immortality - As a demon, he is immortal unless killed. Belphegor mentioned that when he was human, people were worshipping a rock that looks like a penis though it is unclear how long he has been a demon. Belphegor only states that "it was awhile ago" that he was human, indicating he is rather old even by demonic standards.
 * Invulnerability - As a demon, he is invulnerable to all forms of conventional harm.
 * Super Strength - As a demon, Belphegor is stronger than any human and most monsters. He was able to easily punch his bare hand into a dead body to rip out the man's heart.
 * Astral Perception - Even while ghosts are invisible, Belphegor is able to see them.
 * Regeneration - After receiving a slash to the hand from Constance Welch, Belphegor was able to heal the injury.
 * Telekinesis - Belphegor was able to telekinetically fling Castiel out of Lilith's Chamber.
 * Spell Casting - Belphegor displays an impressive knowledge of magic, being able to cast spells to cast souls out of the bodies they are possessing and to set up a barrier to trap ghosts. He also displayed enough control of the barrier to temporarily open a door in it so that Kevin Tran could escape.
 * Torture - Belphegor spends most if not nearly all of his time in Hell endlessly torturing and torturing human souls. His skill in the art of torture is unknown, but he knows the art of torture enough to become a tortuer of Hell.

Weaknesses
Belphegor presumably possesses all of the regular weaknesses of a demon.
 * Higher Demons - Belphegor is weaker and subservient to higher demons such as Lilith and Crowley and is mentioned to have been "bowing and scraping" to them when they were in power. In addition, he was no match for Ardat who easily overpowered Belphegor.
 * Seraphim - Belphegor appeared to be wary of Castiel when threatened by him and was easily pinned against a wall by him. He was later overpowered by Castiel who effortlessly smote Belphegor.
 * Angel Blades - As a seemingly regular demon, he could probably be killed with an angel blade; he was wary of one when Castiel threatened him and Ardat tried to kill Belphegor with one.

Appearances

 * Season 15
 * Back and to the Future
 * Raising Hell
 * The Rupture

Trivia

 * As Jack's eyes are burned out, its unclear what color Belphegor's eyes are. Belphegor himself comments that he'd show his eyes if he could but Jack's lack of eyes prevents that. However, he has stated that he is neither a black-eyed demon nor a crossroad demon. Specifically, he seem to underestimate his own status and rank in Hell's hierarchy, merely referring himself as a worker doing his job.
 * Despite his vessel having no eyes, Belphegor's interactions with the world around him suggest that the demon can see just fine without them. This is contrary to the Waitress demon in Lazarus Rising who was blinded when her vessel's eyes were burned out by Castiel. However, in her case, the demon was possessing the vessel at the time it suffered the injury rather than taking over the body afterwards.
 * Belphegor suggests that the Winchesters and Castiel are responsible for the "hellmouth" situation. In Buffy the Vampire Slayer, hellmouth is place in which dimensional barriers are particularly weak, allowing to relatively easily move between dimensions in such places. Thus, a hellmouth is practically a gateway between different dimensions. Specifically, the town Buffy lives in, Sunnydale, is built just a top a rather dangerous hellmouth, connecting earth with an awful hellish dimension, thus Buffy must prevent from being opened. A second hellmouth is revealed to exist in Cleveland, Ohio in the Buffy series finale.
 * In The Gatekeeper Trilogy of the Buffy the Vampire Slayer novel series, Belphegor is one of the Big Bads.
 * He is the second demon that is confirmed to like Hell, the first being Alastair. This is very rare, as Hell is so awful that even most demons despise and fear it.
 * Coincidentally, both of them were torturers in Hell.
 * Belphegor is similar in some respects to Gadreel as a non-human character who portrays themselves as an ally of the Winchesters while using one of the family, or in Belphegor's case extended family, as a vessel only to betray them for their own purposes.