After winning the Minneapolis Comedy Competition in 1988, Arnold moved to Los Angeles, where he was hired as a writer for the hit TV sitcom "Roseanne." Soon thereafter, he and the show's star, Roseanne Barr, married, and the pair became notorious for their outrageous behavior. Arnold, who often appeared on "Roseanne," later starred in two sitcoms of his own -- "The Jackie Thomas Show" and "Tom."
In 1994, Arnold and Barr went through an acrimonious divorce, and Arnold struck out on his own, surprising critics with strong performances in True Lies and Nine Months. He has since appeared in numerous movies, including the 2005 independent film Happy Endings.