English actor and voice artist John Leeson, best known for voicing the robotic dog K9 in Doctor Who and its spin-offs, died peacefully after “a summer of illness”, according to a 1 November post by his son on Facebook. He was 83.
“Many thanks to the Whovian community for the love they showed to my father over the decades, it meant a lot to him and me,” Leeson’s son, Guy Ducker, shared on a subsequent post.
Leeson, the son of a vicar, was born John Francis Christopher Ducker on 16 March 1943 in Stoneygate, Leicester, England.
He performed at Leicester’s Little Theatre and productions at the St Margaret’s Drama Society as a child. He successfully auditioned for the Royal Academy of Dramatic Art (RADA), which he attended from 1962 to 1964. He adopted a stage name, John Leeson, based on his godmother’s surname. He travelled to the United States to perform Shakespeare. His first role was repertory theatre at Frinton-on-Sea. He later worked in Colchester, Birmingham, Newcastle, and at Nottingham Playhouse. His first London stage show was held by Moral Re-Armament at Westminster Theatre, while his introduction to West End theatre was Plaza Suite at the Lyric Theatre in 1969. His first television role was a French hippie in Crossroads (1967–1968). Leeson became a regular television performer, including in the 1969 Dad’s Army episode Sons of the Sea, 50 episodes of Rainbow (1972), and Sorry! (1981). He continued theatre work, including in Don’t Start Without Me at the Garrick Theatre in 1971.
In 1977, director Derrick Goodwin, cast him as the voice of K9 in the Doctor Who serial The Invisible Enemy. K9 was made a regular character to provide a humorous tone to the program to appeal to children.
After The Armageddon Factor (1979), David Brierley voiced the role until 1980 when producer John Nathan-Turner requested Leeson’s return. Leeson also voiced the character for K-9 and Company (1981), a failed television pilot starring Elisabeth Sladen as Sarah Jane Smith. He later had cameo appearances in The Five Doctors (1983) and Dimensions in Time (1993).
Leeson returned to Doctor Who in the 2006 episode School Reunion alongside Sladen, which led to frequent appearances in the spinoff series The Sarah Jane Adventures (2007–2011). Around the same time, he appeared in another spinoff series, K9 (2009–2010). In 2013, he voiced K9 in the Doctor Who 50th anniversary comedy homage The Five(ish) Doctors Reboot.
Leeson appeared in two episodes of Blake’s 7. Other credits include the voice of Jigg in Jigsaw. He was one of the resident team of actors in stunts for Game for a Laugh (1981–1985) and he portrayed several different characters in Beadle’s About (1986–1987, 1992).
His film credits included the Hunt Secretary in Tarka the Otter (1979) and a professor in Miami Connection (1985).He worked as a continuity announcer for several networks, including BFBS Television, the BBC, and Channel 4, and he read extensively for the Calibre Audio Library. He narrated and provided voices for The Space Gypsy Adventures on Children’s UK hospital radio.
In 2026, Leeson reunited with Tom Baker in the Kickstarter-funded audio drama series Sir Sherlock, playing Dr. Watson to Baker’s Sherlock Holmes.
As tributes continue to pour in from former colleagues and the Doctor Who community, Leeson is remembered not just as a remarkably versatile performer, but as a true gentleman who transformed a metallic television prop into a treasured and enduring character.