‘Doctor Who’ Says Goodbye to John Leeson, the Voice Who Made K-9 an Icon

Few sidekicks in British sci-fi have been as beloved as a clunky metal dog on wheels. For generations of viewers, the sound of a clipped, mechanical “Affirmative” was as much a part of ‘Doctor Who’ as the TARDIS wheezing into place, and that voice belonged to John Leeson. His work as the Doctor’s robot companion turned a prop into a character with real personality.

Leeson’s journey with K-9 began in 1977, when he was asked to play 2 voices in the Fourth Doctor story ‘The Invisible Enemy.’ One was the Nucleus, the other was Professor Marius’s robot dog, K-9. His take on the machine was so successful that producer Graham Williams decided to make the character a regular and put Leeson on contract.

The wider ‘Doctor Who‘ family is now mourning his loss. John Leeson died on November 1, 2026, at the age of 83. His son, Guy Ducker, announced the news to friends and fans, saying his father passed away after an illness over the summer.

Tributes arrived quickly, including one from ‘Doctor Who’ showrunner Russell T Davies, who brought Leeson back to the franchise in the revived series. Fans have been sharing their memories of the voice that defined one of the show’s most enduring companions.

What made Leeson’s performance special was that he never played K-9 as an animal. In a 2014 interview, he recalled that Williams described a character who held and delivered information, with a voice that should sound as though it came through the small speaker of a cheap radio. Leeson raised his voice and clipped the delivery to create that mechanical quality.

The approach worked because K-9 was a knowledgeable machine rather than a pet. That distinction gave the character a dry, loyal charm that audiences adored, even when the production props were famously temperamental. Tom Baker, who played the Fourth Doctor, reportedly detested the character but shared a friendly relationship with Leeson.

Leeson’s connection to K-9 was far from a straight line. He grew worried that appearing only as a voice would hurt his chances of landing visible roles, so he stepped away, and David Brierley voiced the character for the 1979 to 1980 season. Leeson returned for the next season at the request of producer John Nathan-Turner, as K-9 was being written out of the series.

He went on to voice the character in the 1981 spin-off pilot ‘K-9 and Company,’ alongside Elisabeth Sladen as Sarah Jane Smith. He also appeared in the anniversary special ‘The Five Doctors.’ In total, he voiced the Doctor’s robot dog in 54 episodes of the main series.

When Davies was writing the 2006 episode ‘School Reunion,’ dealing with Sarah Jane Smith’s return, he brought Leeson back as K-9 alongside David Tennant’s Doctor. The appearance reintroduced the character to a new generation and led to more work in ‘The Sarah Jane Adventures,’ where Leeson voiced K-9 from 2007 to 2010. He also voiced the character in the 2009 to 2010 spin-off series ‘K9’ and in many audio dramas.

It was a rare second act for a performer tied to such a distinctive role. Leeson could easily have been typecast, but instead the franchise kept finding reasons to bring him home.

Leeson was born John Ducker in Leicester on March 16, 1943, and adopted his stage name using the surname of his godmother. He trained at the Royal Academy of Dramatic Art, where he studied alongside Terry Hands and Susan Fleetwood. His television credits stretch across ‘Blake’s 7,’ ‘Jigsaw,’ ‘Crown Court,’ ‘Minder,’ ‘Vanity Fair,’ ‘The Bill’ and ‘Doctors.’

He was also known to children’s television viewers for playing Bungle in ‘Rainbow’ and worked as a continuity announcer on Channel 4. It was a varied career, but one that will always return to the faithful voice at the Doctor’s side.

The Doctor has had many companions across the decades, but few have inspired the same warmth as K-9. A lot of that affection traces back to the person behind the speaker, whose performance gave a small, awkward robot dog a heart. Leeson leaves behind more than 100 screen and audio credits and a character that fans of every generation recognize instantly.

What is your favorite K-9 moment, and what will you remember most about John Leeson’s work? Share your thoughts in the comments.