The Poltergeist is believed to have a curse mostly called the "Poltergeist curse" In both movies "1 and 2" they used real corpses which may have been the start of the curse. Shortly after the movie's came into place the cast from the 1st and 2nd died off. It is kind of eerie how in the 3rd movie when they "Didn't" use real corpses no one died. Not only was it the death's but when shooting the movie strange things begin to happen as in picture frames being moved around, evil clown doll's choking people (no one died from that) Also when the soundtrack came out one of the actors "Dominique Dunne" went to start filming another movie when her abusive ex boyfriend showed up and strangled her. Creepy part about it was the theme song http://www.youtube.com/watch?v=WHtPa834UhQ&feature=related was playing when it happened. Believe it or not but there was something odd about that movie.
List of deaths and
For more information go to http://thebeyond.info/poltergeist.php