Colley was born on 7 December 1937 in
Manchester. One of his early appearances on British television was as Noah Riley in the 1970s police drama
The Sweeney, in an episode entitled
Trap. He played
Jesus in ''
Monty Python's Life of Brian, having also appeared in the earlier Monty Python-related production Ripping Yarns episode "The Testing of Eric Olthwaite" alongside Michael Palin. In 1982, he had the lead role of Horatio Nelson in the TV period drama I Remember Nelson''. Colley worked extensively with British director
Ken Russell from the early 1970s to the early 1990s as part of a repertory of actors who appeared across Russell's television and film work. He played the role of
Modest Tchaikovsky in the film
The Music Lovers (1971). He went on to play the role of LeGrand in Russell's
The Devils (also 1971); he played the journalist Krenek in the biopic
Mahler (1974); the composer
Frédéric Chopin in
Lisztomania (1975); Mr Brunt in Russell's adaptation of
The Rainbow (1989) by
D. H. Lawrence. and as the composer
John Ireland in
The Secret Life of Arnold Bax (1992). For his work in the
Star Wars franchise, Colley's role as
Admiral Piett is noted for differing from the other ill-fated Imperial officers who appeared alongside him in
The Empire Strikes Back (1980), as Colley was the only actor to play an Imperial officer in a second
Star Wars film, reprising his role in
Return of the Jedi (1983). Coincidentally, Colley and Darth Vader actor
David Prowse had a part in the fantasy film
Jabberwocky (1977). Colley also played a notable role in the 1982
Clint Eastwood film
Firefox, where he played a
Soviet colonel tasked with the protection of the Firefox and its secrets. He went on to play
SS-
Standartenführer Paul Blobel in the
Second World War drama
War and Remembrance. In 1990, Colley portrayed Napoleon Bonaparte during his last days in exile on St Helena in Napoleon's Last Battle, a BBC Timewatch documentary drama portraying the last days of Napoleon's life in exile on St Helena. Colley directed
Greetings (2007), a horror film starring Kirsty Cox, Henry Dunn and
Ben Shockley. In 2017, Colley recorded a series of short narrations for inclusion on
Pop Wasteland, an album by
Folkestone band Phenomenal Cat. ==Personal life and death==