William Russell Enoch (born 19 November 1924) is an English actor. He achieved prominence when he took the title role in the ITV television series The Adventures of Sir Lancelot (1956–1957). In 1963, he became part of the original lead cast of BBC1's Doctor Who, playing the role of schoolteacher Ian Chesterton opposite William Hartnell from the show's first episode until 1965.

Russell's film roles include parts in The Man Who Never Was (1956), The Great Escape (1963) and Superman (1978). On television, he appeared as Ted Sullivan in Coronation Street in 1992. In recent years, Russell has maintained his association with Doctor Who; he returned to the show in 2022, making a cameo appearance as Ian in "The Power of the Doctor", 57 years after the character's last television appearance.

William Russell Enoch was born on 19 November 1924 in Sunderland, County Durham,^[1] to Eva Compston (née Pile) and Alfred James Enoch. He was educated at Wolverhampton Grammar School and Oxford University and became interested in acting at an early age.^[2] He was involved in organising entertainment during his national service in the Royal Air Force and then, after university, went into repertory theatre.

In 1963, Russell was cast in Doctor Who as science teacher Ian Chesterton, the Doctor's first male companion, appearing in all episodes of the first two seasons of the programme except the last four.

Russell was one of the four original cast members of Doctor Who, starring opposite William Hartnell as the First Doctor, Jacqueline Hill as Barbara Wright, Carole Ann Ford as Susan Foreman and later Maureen O'Brien as Vicki. His first involvement in the series took the form of the untransmitted pilot episode, which was eventually reshot and broadcast as the first episode of An Unearthly Child, the programme's first serial. He eventually departed, alongside Hill, in "The Planet of Decision", the final episode of The Chase, which served as the penultimate story of the second season.

Russell was intended to reprise the role of Ian in the 1983 story Mawdryn Undead alongside Peter Davison as the Fifth Doctor for the twentieth season. However, scheduling conflicts made him unavailable.^[3]

Since leaving Coronation Street in 1992, Russell has maintained his association with Doctor Who, having lent his voice as a narrator to several of the audiobook releases of the lost 1960s episodes. He appeared in The Game, one of the continuing Doctor Who audio stories produced by Big Finish Productions. He has also recorded readings for some of the CD audio adaptations of Doctor Who story novelisations originally published by Target Books.

In 1999, Russell returned to the role of Ian for the VHS release of The Crusade, of which "The Knight of Jaffa" and "The Warlords", the second and fourth episodes, respectively, are lost. He recorded several in-character scenes to camera, which helped to bridge the gaps between the existing episodes.

Russell has also contributed to the Doctor Who DVD range, having participated in several audio commentaries and on-screen interviews since 2002.

In 2013, the BBC produced An Adventure in Space and Time, a docudrama depicting the creation and early days of Doctor Who, as part of the programme's fiftieth anniversary celebrations. Russell appeared as a character in the drama, portrayed by actor Jamie Glover.^[4] Russell himself had a cameo role, playing a BBC Commissionaire named Harry.^[5]

The same year, Russell portrayed both Ian and the First Doctor in the Big Finish audio play The Light at the End, produced to celebrate the fiftieth anniversary; aged 88, he became the oldest ever person to portray the Doctor,^[6] a record he held until March 2023, when Tom Baker portrayed the Fourth Doctor in the Big Finish audio series The Fourth Doctor Adventures at the age of 89.

Russell made a cameo appearance as Ian in the 2022 special "The Power of the Doctor".^[7] With this appearance, he achieved the Guinness World Record for the longest gap between TV appearances.^[8]

In 1953, Russell married Balbina Gutierrez. They had three children, Robert, Laetitia and Vanessa, and later divorced.^[9]

On 2 December 1988, 64-year-old Russell and his second wife Etheline Margareth Lewis,^[10] a Barbadian Brazilian doctor,^[11] whom he married in 1984, welcomed a son, Alfred. Like his father, Alfred is an actor, best known for playing Dean Thomas in the Harry Potter film series and Wes Gibbins in the television series How to Get Away with Murder.