Voice of Doctor Who’s K9: John Leeson dies at 83 after summer illness
The actor, born John Ducker, provided the character's voice from 1977 until 2025, defying early BBC predictions that the role would end with its debut.
By Tunde Bailey ·
Fans of the long-running sci-fi series Doctor Who lost the voice behind its most famous robotic companion on Monday. John Leeson, the actor who portrayed K9, the metal dog, died at the age of 83. His son, Guy Ducker, confirmed the news on social media, noting that his father had suffered from a summer of illness before passing peacefully.
Leeson, who was born John Ducker in 1943, trained at the Royal Academy of Dramatic Art before building a career in theater and television. His credits included roles in Dad’s Army, Sorry!, Crown Court, and Longitude. He also worked as a continuity announcer for Channel 4. However, his most recognizable work remained the voice of K9, a character created by Bob Baker and Dave Martin.
The robot dog first appeared in a 1977 story titled The Invisible Enemy, starring Tom Baker. Although the writers initially planned for K9 to appear in only one script, producers believed the character would appeal to younger audiences. They added the metallic dog to the Tardis team, where it remained until 1981. Leeson established the character's catchphrase, "Affirmative, Master," during this period, though David Brierly also voiced the role for a time.
Leeson returned to the character for the 20th anniversary special and the spin-off series K-9 and Company. He reunited with actress Elisabeth Sladen, who played Sarah Jane Smith, for the 2006 episode School Reunion. The two later starred together in the CBBC series Sarah Jane Adventures, which ran from 2007 until Sladen’s death in 2011. Leeson continued working in the franchise, providing voices for Big Finish audio dramas as recently as 2025.
Former showrunner Russell T Davies paid tribute to Leeson on Instagram, stating there was no question about asking him to voice the robot when it returned. Davies described the character as a posh, uppity, and haughty dog that was also wry and innocent. He noted that Leeson pitched the voice perfectly so children could imitate it, calling the actor a true gent and a great loss.
Colleagues in the production industry remembered Leeson for his professional demeanor. Keith Barnfather, a producer of behind-the-scenes documentaries, described him as kind, considerate, and charming. Lisa Bowerman, who has worked across the Doctor Who universe, called him an utterly lovely man and an iconic voice. Leeson himself described his career as split between stage acting and television, which he said arose by accident.
In interviews, Leeson shared anecdotes about his time in costume. He recalled being poured out of a bear suit into a taxi after working in the children’s show Rainbow, explaining that the heat made him feel ill inside the outfit. He also expressed frustration over a bad haircut received for his role in Dad’s Army, noting that the style was hidden by a balaclava and a tin hat, rendering the effort pointless.
Leeson often joked about the longevity of his K9 role. He recalled being told by BBC producers after his debut that no further episodes would be made. Despite that prediction, he remained attached to the franchise for nearly five decades, meeting a tremendous number of people while performing as the robot dog until his final audio work in 2025.
