In the new thriller "Orphan" (out July 24), Peter Sarsgaard and Vera Farmiga play John and Kate Coleman, a couple who decide to adopt a daughter after a devastating miscarriage. But the 9-year-old girl they adopt, Esther (Isabelle Fuhrman), is not what she appears to be, and it's up to Kate to convince her family and friends that something else lays behind Esther's angelic little face. Farmiga has been in this predicament before, in the 2007 indie horror flick "Joshua," but she's just part of a long line of cinematic parents traumatized by the little darlings in their lives.

The "evil child" genre has been with us since at least the 1950s, when rising concerns about juvenile delinquency made "The Bad Seed" into a stage and screen hit. But the idea really took hold in the next two decades, when parents watched in horror as their kids grew their hair, took massive quantities of drugs, and joined the counterculture. It didn't matter whether the movies portrayed the kids as the product of bad DNA, the result of alien experimentation or the spawn of Satan himself; soon, movies like "The Exorcist" were saying that the apples were just plain rotten whether they fell far from the trees or not.

It is perhaps the ultimate horror to imagine that a child, usually such a symbol of innocence, can be corrupted into a twisted, malevolent and unrecognizable source of fear. That's probably why these movies, from "The Omen" to "Orphan," continue to crop up every couple of years. Here's some of our favorites -- and be warned, they don't play nice at all.

("Orphan"/Warner Bros.)