John Leeson, best known for voicing robot dog K9 in Doctor Who and its spin-offs, has died aged 83.
The actor, born John Ducker, was also known for his character work across a range of TV shows such as Dad’s Army, Sorry!, Crown Court and Longitude.
His son, Guy Ducker, announced the news in a Facebook post which said: “I regret to announce the death of my father, John Ducker, a.k.a. John Leeson, at 3:03 pm today after a summer of illness. The end was peaceful.”
He also included a William Shakespeare quote, which said: “Good night, sweet prince, and flights of angels sing thee to thy rest.”
Former Doctor Who showrunner Russell T Davies shared a post to Instagram of Leeson and robot dog K9, his most famous role. The voice of K9, and a fine, fine actor.”
Davies revived Leeson’s character in 2006, shortly after resurrecting the BBC sci-fi series.
Recalling this, he said: “There was no question that we’d ask John to provide the voice, it was impossible to imagine anyone else. And really, what a performance, what a character: a posh dog, uppity, haughty, wry, but somehow innocent too, and so funny.”
“God, he was good,” the 63-year-old continued. “Pitched perfectly so that kids could impersonate him. That’s not easy, that’s hell of a piece of acting. And he was wonderfully dedicated to that character for… gasp, six decades!
“He’d phone me up and chat sometimes – on the landline, I remember, those were the days.
“Including one time when he hadn’t been paid! But he was so gracious about it. A true gent, and a great loss. Sympathy to his family and friends. Good night, sir. Affirmative!”
Leeson trained at the Royal Academy of Dramatic Art before embarking on a successful career on stage and screen.
He was also known for his character work across a range of TV shows such as Sorry! and Longitude.
His early television credits included Dad’s Army and The Spanish Farm. He also played Bungle the Bear in children’s TV series Rainbow.
Leeson appeared in TV drama Crown Court, but his most memorable role came in 1977 in Doctor Who, appearing alongside actor Tom Baker in the fourth incarnation of the title character.
Baker has previously spoken about how he disliked K9, but despite this, the robot dog was a hit with viewers and continued to appear in the show for several years.
Leeson reprised the role in several Doctor Who audio dramas and spin-off series, including CBBC’s The Sarah Jane Adventures, before returning to the original programme following its revival.
His other credits include The Bill, Vanity Fair, Doctors and Blake’s 7, and he was also regularly heard as a continuity announcer on Channel 4.
In 2026, he reunited with his former Doctor Who co-star Baker, who played Sherlock Holmes in the audio drama Sir Sherlock: The Red Letter Day, alongside Leeson as Doctor John Watson.
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