From what I´ve heard, it was a Pagan holiday called Samhain. Then I heard a legend about some sort of mass-murderer called Hallow. When the villagers found out he was the murderer they arrested him and sentenced him to death. Then the day before his execution (Oct. 31st) he cursed the villagers by making the dead rise from the cemetry and haunt them, but because the cemetry was full of his victims they haunted him instead and took him to hell when he was executed. That´s why it´s called Hallow´s Eve. Well that´s the legend I put on my Halloween essays when I was younger anyway, but now I come to think about it it sounds a bit like the Dracula legend.