George Coulouris played Arbitan in the Doctor Who episode "The Sea of Death". One of the most famous actors to appear on Doctor Who in its early seasons, Coulouris began acting in American films in the 1930s. He also appeared in one of the first dramatic programs on US television — broadcast in 1939. Early in his career he was a member of Orson Welles' Mercury Theater of the Air and took part in the infamous The War of the Worlds radio broadcast in 1938, which later formed a major plot point of the audio story Invaders from Mars. Welles' line, "George, what are you doing with those keys?" in that audio drama is an in-joke referring to Coulouris' role in Doctor Who. He later appeared in Welles' masterpiece, Citizen Kane.
Coulouris appeared in numerous Hollywood productions until the 1950s when he returned to Britain and continued as a prolific performer on film, TV and stage into the mid-1980s.
With his appearance in Invaders from Mars, Coulouris is one of only handful of Doctor Who actors (alongside William Hartnell) to also be depicted as actual characters in a Doctor Who story.