is an immortal demon born in prehistoric times. He feasted on mankind's offerings to the dead since the time of Ancient Egypt. He was worshiped as a deity by the druids of Celtic Britain until they were slain by the Romans. He was trapped within a Druid Tome during the Middle Ages and released in modern times accidentally by the Scarlet Witch. Samhain attempted to be reborn by using the Scarlet Witch's magic, and turned three trick-or-treaters into monsters based on their costumes. While the Vision and Jarvis battled the trick-or-treaters, the Scarlet Witch was forced to battle Samhain alone. Samhain was defeated when the Scarlet Witch used her magic to send the Druid Tome into a fire
Samhain returned following the Scarlet Witch and Vision's return to Leonia. While the Vision enjoyed a magic show performed by Glamour and Illusion, the Scarlet Witch attempted to contact the spirit of Agatha Harkness. Instead, she
was captured by the spirit of Thornn. Samhain planned to be reborn inside the Scarlet Witch's unborn child and soon she was battling the spirits of the Salem Seven and the Legion of the Unliving. Meanwhile Agatha managed to contact the Vision through Glamour and Illusion's magic show. Illusion suspected that the Druid Tome wasn't fully destroyed during the first battle against Samhain and as long as even ashes remained, Samhain could still return.
With the help of Holly LaDonna and Illusion's powers the Druid Tome was reformed. The Vision then used his Solar Beam to disintegrate the book completely. With this Samhain lost his form and was transformed into energy. The spirit of Agatha Harkness then trapped Samhain's energy into the Spirits of the Salem Seven. With his spirit split up and the Druid Tome completely destroyed, Samhain could never return.
Samhain claims to have been born by the terrors of the cavemen. He is able to detect any kind of magic. His magical knowledge allows him to create winds at will, transform humans into magically powered slaves and create insects and lizards out of thin air. His scythe allows him to reveal to others images of his own past. On Halloween Samhain serves as the leader to ghost present at the Land of the Dead.