John Leeson, the actor best known as the voice of K9, the robot dog in Doctor Who, has died at 83.Leeson’s son, Guy Ducker, shared the news on Facebook. He wrote: “I regret to announce the death of my father … after a summer of illness.

The end was peaceful.”In a separate post on social media, Ducker said: “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.”Born John Ducker in 1943, he trained at the Rada before embarking on a successful career on stage and screen. He was known for his character work across a range of TV shows such as Dad’s Army, Sorry!, Crown Court and Longitude, while other credits included The Bill, Vanity Fair, Doctors and Blake’s 7.

He was also a continuity announcer on Channel 4.But Leeson was best known for K9, created by Bob Baker and Dave Martin, who was introduced to Doctor Who in 1977 in a Tom Baker-led story called The Invisible Enemy.Originally only intended to appear in that single script, the production team believed the character would be popular with younger viewers, and decided to have the metallic mutt join the Tardis team. He stayed until 1981 – although K9 was also voiced for a period by David Brierly – establishing the catchphrase “Affirmative, Master” when addressing the Doctor.Leeson marries Judy Griffiths in Kensington, west London, in August 1969.

Photograph: Gary Weaser/Getty ImagesK9 flanked by the stars of Doctor Who in 1993. Photograph: Maximum Film/AlamyLeeson stands amid an ITV audience in 1993.

Photograph: ITV/ShutterstockLeeson reprised the role in the 20th anniversary special of Doctor Who and in a spin-off K-9 and Company, which featured Elisabeth Sladen as popular companion Sarah Jane Smith. Sladen and Leeson were reunited in Doctor Who in 2006 in a David Tennant episode called School Reunion, before featuring in the CBBC spin-off Sarah Jane Adventures, which aired from 2007 until Sladen’s death in 2011.In an Instagram post after Leeson’s death, the former Doctor Who showrunner Russell T Davies said: “There was no question that we’d ask John to provide the voice” when the robot returned. “A posh dog, uppity, haughty, wry, but somehow innocent too, and so funny.

Pitched perfectly so that kids could impersonate him. That’s not easy.

A true gent, and a great loss.”Keith Barnfather, who first worked with Leeson in the 1980s and who produces behind-the-scenes documentaries about Doctor Who, described the actor as “kind, considerate, professional, charming, talented, unassuming”. Lisa Bowerman, who has credits for work across the Doctor Who universe, remembered him as “an utterly lovely man, excellent company and – and I don’t hesitate to use this word for once – a truly iconic voice”.After leaving school, Leeson worked as a hospital porter before auditioning for Rada.

Talking about his career in interviews, Leeson described it as being in two parts: “Half of my career has been pretty much as a stage actor and the television half of my career arose pretty much by accident.”The stars of Rainbow, from left: Bungle, Zippy, George and Geoffrey Hayes. Leeson said he felt ‘really ill inside this bear suit’.

Photograph: Rex/ShutterstockLeeson had a stint playing Bungle on the children’s show Rainbow, a job in which he described being “poured out of this costume every evening into a taxi”, because a day’s work in a small studio under the hot lights left him “really ill inside this bear suit”.He also once lamented the haircut he was given when appearing on Dad’s Army, saying “I was livid because they gave me an army haircut, a real basin job, and then of course put me in a balaclava and a tin hat, so nobody could see the hair anyway.”He was still working as K9, providing voices for Big Finish audio dramas last year. This was despite, he once said, being told by producers at the BBC after his debut that “under no circumstances would there be anything after the first episode has been shot and is in the can.

So don’t expect too much. And here I am in 2025 still attached to Doctor Who … I got to meet a tremendous number of knees doing K9.”Leeson with the beloved K9.

Photograph: Shutterstock