From an Anglo Irish family. Born in London but educated in Ireland. Graduated from the Royal Academy of Dramatic Art 1956-58 then 12 years as Associate Artist with the Royal Shakespeare Company. Appeared on Broadway in 1966 with "Marat-Sade" and later in 1975 with "Sherlock Holmes". He won the Los Angeles Drama Critics Circle award for "The Homecoming" in 1995, at the Matrix Theatre.


Was the runner-up for the role of Ambassador G'Kar on "Babylon 5" (1994). Father of Mark Sheppard. Has appeared as different characters in four incarnations of Star Trek. He was the warden of the Klingon penal colony in Star Trek VI: the Undiscovered Country (1991), Dr. Graves in the Star Trek: The Next Generation episode The Schizoid Man (#2.6), Qatai in the Star Trek: Voyager episode Bliss (#5.14), and as the Vulcan Science Minister in Star Trek (2009).