Moriarty played Executive Assistant District Attorney Benjamin Stone for the first four seasons (1990–1994) on the television show "Law & Order." Moriarty is also known for his roles in movies such as "Bang the Drum Slowly", "Who'll Stop the Rain", "Q: The Winged Serpent", "The Stuff", "Pale Rider", "Troll", "Courage Under Fire", and "Shiloh".