Born in New Rochelle, N.Y., on Feb. 18, 1964, Dillon made his silver-screen debut at age 15 playing a school bully in Over the Edge (1979). Several similar teen films followed, including My Bodyguard (1980) and Little Darlings (1980). Dillon landed his breakout role in 1983's The Outsiders, and by the mid-1980s he'd transitioned into the adult sphere.
In 1989, Dillon gave a gritty, critically acclaimed performance as a junkie in Drugstore Cowboy. He also delivered memorable turns in A Kiss Before Dying (1991), Singles (1992), To Die For (1995), Albino Alligator (1997), In & Out (1997), Wild Things (1998) and There's Something About Mary (1998).