Bloody Mary - Yes, the urban legend about the chick that you call out to three times in the mirror and she is said to appear rocking in a rocking chair all bloody (at least the way I heard it). Its different for all of us, depending on the era you grew up in, locale, and who you heard it from. The legend stems from Queen Mary I. Mary was Queen of England and Ireland from July 1553 until her death on November 17, 1558. Her executions of Protestants earned her the name "Bloody Mary".
Reverend Henry Kane (Poltergeist) - Poltergeist II: The Other Side develops the character Reverend Henry Kane further than in the first Poltergeist Movie. He was the leader of a utopian cult, who sealed themselves in an underground cavern waiting for Armageddon. This cavern was under Carol Anne's house. He wishes to possess Carol Anne to continue manipulating his followers after death.
Carlos Malfeitor (Witchboard) - is the evil spirit in the Ouija board that pretends to be a little boy named David and eventually possesses Tawny Kitaen (Linda). He carries an axe, isn't a nice guy at all, and has really creepy eyes and has always scared the shiat out of me, whether you think he's scary or not! Yuck, I hate him!