Ritter appeared in over 100 films and television series combined and performed on Broadway, with roles including adult Ben Hanscom in "It" (1990), "Problem Child" (1990), "Problem Child 2" (1991), and "Bad Santa" in 2003 (his final live action film, which was dedicated to his memory). In 2002, Don Knotts called Ritter the "greatest physical comedian on the planet". His final roles include voicing the title character on the PBS children's program "Clifford the Big Red Dog" (2000–2003), for which he received four Daytime Emmy Award nominations, as Paul Hennessy on the ABC sitcom "8 Simple Rules" (2002–2003) and an uncredited role for providing the normal voice as Three in "Seven Little Monsters" (2000–2003).