Samhain

Samhain is the core of Halloween, and a very special demon. So special that he can only leave Hell when summoned by two powerful witches through three blood sacrifices over three days, the last on the final day of harvest, which is the 31st of October, Halloween. Once Samhain has risen, he is able to raise ghosts, zombies, and Ghouls and unleash them onto the world.

Background
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.

Personallity
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 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. He also had a very violent and ferocious side to his personallity, although willing to use his powers to dispatch attackers, unlike most demons, he was also more than willing to enter physical combat, and try and rip them appart 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 snalling like a wild animal.

Powers
In the episode "It's the Great Pumpkin, Sam Winchester" Samhain shows multiple abilities. The fact that his release was one of the 66 seals, is proof of his great power.


 * Summoning and control over monsters - Sam tells Dean that Samhain, if risen, will have the ability to raise monsters such as zombies to do his bidding. This is proven when Samhain locks a group of students in a mausoleum and causes the corpses to become zombies, to attack them. He also manages to rise at least one ghost before he was exorcised. 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 thought would come to him.
 * Telekinesis- As a powerful demon, Samhain is telekinetic, he used this to free the Zombies from their tombs, so they could kill the students.


 * White Light- Samhain shares the ability to have the fiery white light emanate from his palms, with Lilith, thus further demonstrates his great power. However Sam is still immune to this, as he is with Liliths.


 * Superhuman Strength- Standard demon power (he is probably stronger than most Demons).
 * Superhuman Duribility- Stardard demon power.
 * Superhuman Stamina- As a demon, Samhain never tires.


 * Possession- Like all Demons, Samhain can possess a living or recently deceased human's body.
 * Immunity to iron- Unlike all other demons, Samhain is not harmed by iron, he was able to close an iron gate, and playfully touched it with his hand as he walked away.

Weaknessess
It is possible that he can be wounded by Ruby's knife, since he made sure to get rid of it when Sam tried to cut him with it. Although it glowed, it did not seem to have much of an affect on him, as he casually knocked it out of Sams grip.

He also cannot see people properly if they are wearing masks and costumes.

Since he is a demon, he can be exorcised by Sam, although he was more resilent to Sam's powers than an average demon. It took all of Sams 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.

Season 4

 * "It's the Great Pumpkin, Sam Winchester"