In an interview, he stated, "My father was a producer of radio commercials and from an early age I would accompany him to recording sessions.
I met some of the finest voice talent (Jerry Stiller, Anne Meara, Mel Blanc, June Foray etc.)
"[2] Clotworthy starred as the voice of Jim Raynor in the StarCraft series of real-time strategy video games.
[9] Clotworthy has guest starred on The Big Bang Theory, Two and a Half Men, and China, IL.
In 2014, he 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.