- "Now, hold on to yourselves. There's one more thing: a terrible presence is in there with her. So much rage, so much betrayal - I've never sensed anything like it. I don't know what hovers over this house, but it was strong enough to punch a hole into this world and take your daughter away from you. It keeps Carol Anne very close to it, and away from the spectral light. It lies to her - it says things only a child can understand. It has been using her to restrain the others. To her, it simply is another child. To us, it is the Beast."
- — Tangina Barrons about the Beast (Reverend Henry Kane).
Reverend Henry Kane is the main antagonist of the Poltergeist film series (although in the original movie he was simply named "The Beast") - in life he was a leader of a Satanic, 19th century utopian cult who held an apocalyptic view on the world, sealing himself and his followers inside a cave system in area to die: this location would eventually be built over to make the home the Freeling family would reside in within Cuesta Verde in California. This origin story contradicts the original movie's plot but seems to be the official story of the sequels.
Due to Kane's evil deeds and insanity, he became the "Beast" and held the souls of his followers prisoners in the afterlife and feed off their power to make himself a demonic force. That along with the prisoners of different people who were buried in the same area they died in known as Cuesta Verde. Kane targeted the young Freeling daughter (Carol Anne) due to her innocence and famously kidnapped her, leading to the confrontation that made up the events of the original Poltergeist movie - eventually Carol Anne was rescued from Kane's clutches by her determined mother and father, though in the end Kane and the other spirits imploded the entire house as a final show of power. The other spirits who are unlike Kane and his cult members escaped his grasp because of the psychic Tangina Barrons who helped the Freelings rescued Carol Anne.
Henry Kane returns in his true form in Poltergeist II: The Other Side. He continued his obsessive pursuit of young Carol Anne Freeling when he came to her at a shopping mall while remaining an unseen force that everyone around Carol Anne are not aware of before her mother Diane and her brother Robbie found her and left the mall.