Samhain

Samhain, also known as the origin of Halloween, is a powerful special demon of Hell, who can only rise when summoned by two powerful witches through three blood sacrifices over three days, that last day on the final harvest, Halloween. Once Samhain has risen, he is able to raise ghosts, zombies, and ghouls and unleash them onto the Earth.

History
Samhain is an ancient demon who was worshipped as a god on Halloween by the ancient celts. When he reigned on Earth on Halloween night, people kept their children in that night. They wore masks to hide from him, carved pumpkins to worship him, and left sweets at their doors to appease him.

Samhain, once summoned by Tracy Davis and Don Harding, possesses the dead body of Don Harding. When he enters the body, the corpse's irises turn milky white, while his pupils stay black, marking him as a different kind of demon than has appeared on the show before. His unique eye color may mean that he is somewhere between the white eyed demons, such as Lilith, and the common black eyed demons.

Personality
Samhain was shown to be cruel, and sadistic, he took pleasure in trapping his hosts students and summoning zombies to devour them, so much so, that he playfully rubbed his hand against the gate as he walked off. He however seemed more intested in simply creating and causing destruction, rather than running it, as rather than consolodating his efforts or powers, he simply passed through the area, causing destruction.

He also showed no loyalty, casually killing Tracy Davis, despite it being her who freed him, and she loved him. He was also shown to be treacherous, and cunning, and had a very violent and ferocious side to his personality. Although willing to use his powers to dispatch attackers, unlike most demons, he was also more than willing to enter physical combat, and try to catch and rip them apart limb from limb with his bare hands.

He was also shown to be quiet, and didn't talk much, also when angry, he would start snarling like a wild animal.

Powers and abilities
Samhain is a powerful demon who displayed multiple unique abilities. The fact that his release was noted by Sam as heavyweight witchcraft and later show to be one of the 66 seals, is proof of his great power. However the full extent of his powers has yet to be revealed as he was exorcised shortly after he was risen.


 * Summoning - Sam tells Dean that Samhain, if risen, will have the ability to summon monsters and force them to do his bidding. It's stated the longer he is free, the more dangerous monsters he would summon to the point where everything the Winchester brothers had ever fought would come to him.
 * Necromancy - An incredibly powerful and unique demon, Samhain possesses the power to summon ghosts, and bend them to his will.
 * Reanimation - Samhain was stated to be able to raise the dead, and control them, this is proven when Samhain locks a group of students in a mausoleum and causes the corpses to become zombies, and then had them attack the students.
 * White Light - Samhain shares with Lilith the ability to emit a fiery blast of white light that can obliterate anything in it's path, which serves as a further testament to the demon's great power. However Sam is still immune to this, as he is with Lilith's.
 * Super strength - He was able to throw Sam across the crypt with great force and minimal effort.
 * Possession - Like all demons, Samhain can possess a living or recently deceased human's body.
 * Invulnerability - Like most demons, very few things can harm Samhain. Interestingly he is immune to iron, as he was able to close an iron gate, and playfully touched it with his hand as he walked away, something no other demon is able to do. He's also more resilient to the Ruby's knife than average.

Weaknesses
It is possible that he can be killed by Ruby's knife, since he made sure to get rid of it when Sam tried to cut him with it. Although he was shown to be more resilent to it than normal demons, as while standard demons find cuts from it agonising and damaging, when Sam cut his arm with it, he appeared no more than uncomfortable. He also cannot see people properly if they are wearing masks and costumes.

Since he is a demon, he can be exorcised as he was exorcised centuries ago (according to Sam). He can also be exorcised by Sam, although he was more resilient to Sam's powers than an average demon. It took all of Sam's strength to hold him in place, and even then, he was able to advance a few feet, and to exorcise him, took so much effort it caused Sam to have a nosebleed. He can also only be summoned once every 600 years.

Appearances

 * Season 4
 * It's the Great Pumpkin, Sam Winchester

Trivia

 * It is possible that, in-universe, Samhain is based on the Celtic legend of Mongfind, a leader who made a false peace with an enemy by giving him poisoned wine. He suspected an assassination, and made Mongfind drink the poisoned wine. Thus she died on 31st October, and the festival, Halloween, came to be named after her. Mongfind lived roughly six hundred years ago, according to legend.
 * Samhain in Supernatural is based on an urban legend that the Ancient Celts prayed to a death deity named Samhain who organized terrible human sacrifices on Halloween. In original Celtic mythology, the deity known as Samhain is associated with cattle and smithery and was a minor deity.
 * Despite the students wearing costumes in the mausoleum, Samhain was able to see them, even though he couldn't see Sam or Dean properly when they were covered in blood.
 * In reality, Samhain is the Wiccan (witchcraft religion) holiday on Halloween where the Wiccans celebrate their dead ancestors, based upon an older celtic holiday of similiar name.