The actor hired to voice a robot dog for a single “Doctor Who” story instead spent decades answering to the Doctor with words that generations can still recite.

John Leeson, the British actor who voiced K9 on the BBC science-fiction series “Doctor Who,” died Sunday, Nov. 1, 2026, at 83. In one of his final interviews, he urged the show to raise its game.

Leeson told BANG Showbiz the series needed more from its scripts. “It needs clever ideas, really, somewhere to take viewers that they haven’t been before, and some means of exciting viewers intellectually, as well as just simply by way of entertainment,” he said. He also said of the show’s future: “It’s very much a part of the fabric of British television.”

His son, film editor Guy Ducker, 54, announced the death on Facebook. “I regret to announce the death of my father, John Ducker, a.k.a. John Leeson, at 3.03pm today after a summer of illness. The end was peaceful,” he wrote. Ducker thanked the “Doctor Who” community for the support given his father’s work over the decades, and ended the announcement with a line from “Hamlet”: “Good night, sweet prince…”

A Posh Dog, Uppity, Haughty

Russell T Davies, the former “Doctor Who” showrunner, led the tributes on Instagram, calling K9 “a posh dog, uppity, haughty, wry, but somehow innocent too, and so funny.” He went on: “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.” Davies called Leeson “A true gent, and a great loss.”

David Tennant, who played the Doctor when K9 returned to the revived series in 2006, said Leeson gave the robot dog “something no special effect could supply, a personality that generations would love.”

Keith Barnfather, a producer of behind-the-scenes “Doctor Who” documentaries who first worked with Leeson in the 1980s, remembered him as “kind, considerate, professional, charming, talented, unassuming.” Lisa Bowerman called him “an utterly lovely man” with “a truly iconic voice.”

On All Fours in Rehearsals

K9 debuted in the 1977 serial “The Invisible Enemy,” alongside Tom Baker’s Fourth Doctor. The writers Bob Baker and Dave Martin created the character for that story alone, but producer Graham Williams and script editor Robert Holmes saw the appeal, and Leeson’s performance was a factor in turning a one-off prop with a laser in its nose into a recurring companion.

His clipped delivery of the catchphrase “Affirmative, Master.” carried comic timing rather than mechanical monotony, and the dry confidence played against Baker’s unpredictable Doctor. Leeson once described K9’s personality as “pedantic arrogance and perky one-upmanship.” In rehearsals he sometimes moved around the studio on all fours, so other actors had something to play against.

Leeson voiced the character throughout Seasons 15 and 16, then declined to return for Season 17, when David Brierley took the role. He came back for five serials in Season 18. The character’s regular appearances in the series ended in 1981.

The Reunion With Sarah Jane

Leeson voiced K9 in the 1981 spin-off pilot “K-9 and Company,” which starred Elisabeth Sladen as Sarah Jane Smith, and in the 1983 anniversary special “The Five Doctors.” He reunited with Sladen in the 2006 Tennant episode “School Reunion” and worked with her again on “The Sarah Jane Adventures.” He voiced K9 in “Journey’s End” in 2008, and the audio dramas continued, with Big Finish productions as recently as 2025.

From Hospital Porter to RADA

Born John Francis Christopher Ducker in Leicester on March 16, 1943, the son of a clergyman, he joined the Leicester Drama Society as a young man and worked as a hospital porter before entering the Royal Academy of Dramatic Art in 1962. Leeson was his professional surname, and he built his career in repertory theater.

He played the original Bungle on the ITV children’s series “Rainbow” in 1972, appearing in the first 50 episodes, and took the role of Dugeen in the 1979 “Doctor Who” serial “The Power of Kroll.” His other television work included “Dad’s Army,” “Blake’s 7,” “Crown Court,” “The Bill,” “Doctors,” “Sorry!” and “Longitude,” and he spent time as a Channel 4 continuity announcer. Earlier in 2026 he played Dr. Watson opposite Tom Baker’s Sherlock Holmes in the audio drama “Sir Sherlock: The Red Letter Day.”

Leeson also wrote about wine, and published a memoir in 2011, “Flight of the Budgerigar,” later reissued as “Tweaking the Tail.” His wife, Judy, and his son, Guy, survive him.