O'Donnell started his acting career in the '90s with “Men Don't Leave” (1990). With movies such as “Fried Green Tomatoes” (1991), “Scent of a Woman” (1992) and "The Chamber" (1995), he gained stardom. One of his most memorable roles was playing Batman’s sidekick Robin in "Batman Forever" (1995) and "Batman and Robin" (1997).