Clotworthy has worked in over 100 feature films and television programs. He appeared as "Forensic Technician" in four episodes of the 1980s U.S. TV series Hunter. Clotworthy was the narrator on the Emmy nominated documentaries Empire of Dreams: The Making of the Star Wars Trilogy and Star Wars: The Legacy Revealed. Clotworthy even worked on The Lego Movie Videogame. Clotworthy also narrated Indiana Jones and the Ultimate Quest and Batman Unmasked: The Psychology of the Dark Knight. Clotworthy is also known for voicing the character Marshall Law in both Tekken 5 and its expansion, Tekken 5: Dark Resurrection. He has guest starred on The Big Bang Theory, Two and a Half Men and on China, IL. In 2014, Clotworthy voiced the Espheni (referred to as "The Monk") in the TNT series Falling Skies, and made an on-screen appearance in American Sniper as a Veteran Affairs Doctor who consults with Chris Kyle. Clotworthy also voiced the Black Knight, Zelgius, and Finn in Nintendo's mobile title, Fire Emblem Heroes.