Stuart Milligan is an American actor based primarily in the United Kingdom, best known for his recurring role (1998–2010) as Adam Klaus in Jonathan Creek.
He played a US Navy Drill Instructor in the 1982 black comedy Whoops Apocalypse (London Weekend Television for ITV), then garnered further TV appearances in Chalk and Secret Army.
He portrayed Mr. Green in the CD-i editions of the boardgame Cluedo (1994–95, later remade into a CD-Rom game in 1997), in addition to providing voices for the English dub of Robin Hood no Daibōken.
In 1988, Milligan played the title role in the BBC Radio 4 docudrama Superman On Trial, written and directed by Dirk Maggs.
He played U.S. President Richard Nixon in the Doctor Who episodes "The Impossible Astronaut" and "Day of the Moon" as well as for a special prequel released online.