Mark Andreas Sheppard (born 30 May 1964) is a British-American actor and musician. He is often credited as "Mark A. Sheppard". Sheppard is known for playing the demon/King of Hell Crowley on Supernatural and for his recurring roles as lawyer Romo Lampkin on the Battlestar Galactica reboot, Interpol investigator James Sterling on Leverage, and small-time crime lord Badger on Joss Whedon's Firefly.
At 15, he became a professional musician and enjoyed many years as a recording and touring artist with bands including Robyn Hitchcock, the Television Personalities and the Irish group Light a Big Fire. Mark played drums on Light a Big Fire's second album. As a session musician, he recorded albums for many groups throughout Europe, and eventually moved to the United States.
Sheppard starred in the American production of the play Cock and Bull Story (directed by Midnight Express author Billy Hayes), for which he won numerous awards, including the 1992 L.A. Drama Critics' Circle award, and the LA Weekly and Dramalogue awards.