A film charity announced on Friday that it had found two previously lost 1960s episodes in film cans wrapped in plastic bags among the possessions of a deceased collector.
They have been restored by BBC archivists and will be available next month on the broadcaster's streaming service.
The discovery leaves 95 episodes still missing from the adventures of a galaxy-hopping alien known as the Doctor that debuted in 1963.
Doctor Who — the "who" is an existential question, rather than the character's name — has become a television institution with millions of fans around the world. But the BBC's attitude to the show in its early years was careless. Scores of episodes were lost because the broadcaster threw out film recordings or wiped video tapes for re-use.
The episodes aired during the show's third series in 1965 and feature William Hartnell, the first of more than a dozen actors to play the Doctor, in a story involving arch villains the Daleks – pepperpot-shaped metal aggressors whose favourite word is "Exterminate!"
The newfound episodes feature Peter Purves, who played the Doctor's sidekick Steven Taylor in 46 instalments of the show.
"Twenty-seven of mine still are missing, but I'm delighted that two have been found," 87-year-old Purves told the BBC.
"It's rather sad, but it's great when some turn up."
The discovery is the first since 2013, when nine missing episodes were found in the storeroom of a television relay station in Nigeria.
The newly recovered episodes form part of a 12-part storyline, much of which is still missing.
Doctor Who ran from 1963 to 1989 and was revived in 2005. Its longevity is due partly to the flexibility of the premise. The Doctor, a Time Lord from the planet Gallifrey, can travel to any point in space or time and can regenerate into new bodies, allowing the character to outlive any particular star.
The most recent series, starring Ncuti Gatwa as the Doctor, aired in 2025. The show is due to return with an as-yet undisclosed actor in the role.
