If Peter Pan suddenly fell prey to a bad case of demonic possession, the malicious sprite might come across the way Christian Slater does in the black-comedy hit Heathers. Slater's name may not be a household word yet, but his face, at 19, is already familiar: In 1986's The Name of the Rose, he played Sean Connery's apple-cheeked ecclesiastical sidekick, who was seduced by a libidinous wench. In Tucker, he was Jeff Bridges's apple-cheeked eldest son, as loyal and steel-willed as his inventor pop. Now meet J.D., the apple-cheeked, black-hearted, psychopathic prime remover of several members of his high school class. J.D. has it in for the in crowd, so he eliminates it, one snob at a time: He gives one girl (Kim Walker) a poisoned hangover cure that sends her gurgling and crashing through a glass table. Then he masterminds the shooting of two football stars, and for a capper he tries to blow up the school. So what's a nice boy like him doing in a bloodthirsty number like this? "It's not often at my age that you get a role like that," says Slater. "But after playing really nice kids, I thought, 'Why not a sadistic killer?' It keeps me on my toes."

Heathers director Michael Lehmann admits the squeaky-clean young actor "wasn't exactly what I first thought of as J.D., but Christian has an idiosyncratic quality—he isn't your standard-issue male teenage lead. Very few actors his age can play as wide a range." Adds his friend actor Robert (Chances Are) Downey Jr., in showbiz patois: "He's, like, very Nicholson with some serious Spencer Tracy happening."

Slater's co-star Winona Ryder, who plays J.D.'s girl, claims to have found all this sometimes a bit too spooky for comfort. "He freaked me out during some of those scenes," she confesses. "I got so scared of him, I fled back into my trailer and locked the door." And though it is said to be mere coincidence, Kim Walker and Slater, who had been heartthrobs offscreen for three years, broke up shortly after she went through the glass table.

A lady-killer—though only figuratively—in real life, Slater should have no trouble finding a replacement. His parents, L.A. stage actor Michael Gainsborough and casting executive Mary Jo Slater, divorced when he was 5, and winning affection has always been one of his priorities. "When I was a kid, I had a love affair with my pillow," says the native New Yorker. "My pillow and I got along extremely well, so I knew women were for me." At 7 he appeared on the ABC soap One Life to Live, and the cast and crew applauded his first scene. "That was it," he says. "I was hooked." The next year he toured in The Music Man. In 1985 he made his first feature film, The Legend of Billie Jean, and he has also performed in several Broadway plays, including Macbeth with Nicol Williamson, playing Macduff's son. In the recent film Gleaming the Cube, he played a skateboarder investigating his brother's death.

Despite his long string of credits, Slater hardly seems old for his age. "I'm very mischievous," he says proudly. "A couple of days ago, I ran around and stole the doormats from my neighbors. I just wanted to stir things up a little. I still have 'em." One of his favorite pastimes is Nintendo, and the Westwood apartment he now shares with an 85-pound Akita named Winston could pass for an F.A.O. Schwarz branch. "I spend a lot of time in toy stores," Slater admits, and his mother recalls that after shooting the explicit love scene in Rose, Christian "went home and played with his Star Wars figures." Being a ladies' man with a boy's psyche is just fine with him. "Maybe if I have time for myself, I can do stuff like take cooking classes and grow as a person and all that malarkey," he says. "But for now, I just don't want to grow up."

—John Stark, Marie Moneysmith in Los Angeles