A somewhat obscure myth, folklore holds that vampires originated with Judas Iscariot, betrayer of Christ for 30 pieces of silver. When Judas tried to return the silver and could not, he cast it away as something hateful to himself. Because Judas had betrayed Christ to the Romans, he and his family were cursed.
The Bible holds that Judas committed suicide because of his guilt; suicides in vampire folklore were very likely to come back as vampires, so this may have helped contribute to the belief that vampires originated with Judas.
Also, vampires descended from Judas were usually identifiable by their red hair. This probably points to the origin of the myth among the Greeks, as they believed red hair to be a mark of vampirism. Among the dark Greek, red-hair would certainly seem strange, but among people farther north, closer to the Scandinavian countries which feature such hair, there would be little to no stigma attached to it.
3 Then Judas, which had betrayed him, when he saw that he was condemned, repented himself, and brought again the thirty pieces of silver to the chief priests and elders,
4 Saying, I have sinned in that I have betrayed the innocent blood. And they said, What is that to us? see thou to that.
5 And he cast down the pieces of silver in the temple, and departed, and went and hanged himsef.
(Matthew 27:3-5)
In the manga series Hellsing, the Iscariot Organization is a top-secret wing of the Vatican charged with the active pursuit and extermination of demons (such as vampires) and heretics. Iscariot has a sacred duty to do battle with the “seven million, four hundred and five thousand, nine hundred and twenty-six demons of hell”.