
A pivotal moment in Doctor Who history happened 59 years ago today, fundamentally changing the show. Doctor Who is nearing its 62nd anniversary, having first aired on the BBC on November 23, 1963. But three years later, another event occurred that would significantly influence the Doctor’s future adventures, making it an equally important milestone for this beloved series.
Exactly 59 years ago, on October 29, 1966, viewers witnessed the very first on-screen Doctor regeneration. During a fight with the Cybermen in the fourth season of Doctor Who, specifically the partly-lost story “The Tenth Planet,” the First Doctor, played by William Hartnell, became ill. The final episode aired on October 29, 1966, and showed the First Doctor collapsing and transforming into Patrick Troughton’s Second Doctor, right in front of his companions, Polly and Ben Jackson. Troughton officially took on the role in November 1966 with “Power of the Daleks,” and Doctor Who was forever changed.
How Doctor Who’s Regenerations Have Become More Important in Recent Years

The concept of Time Lords in Doctor Who being able to completely renew themselves – changing every cell in their body when sick, hurt, or aging – originally came from producer John Wiles and script editor Donald Tosh. While William Hartnell’s health was failing, the show’s team needed a way to continue with a new actor, and Ines Lloyd, who took over from Wiles, is often credited with developing the details of how this biological process works. Over the years, the Doctor has regenerated nearly 20 times, and the way it happens has evolved significantly.
For a long time, it was believed Time Lords could only regenerate into 13 different bodies, and the Doctor had already gone through eleven of them, most recently portrayed by Matt Smith. The Time Lords supposedly gave him another chance at life with a new regeneration cycle. However, recent stories, especially Jodie Whittaker’s time as the Thirteenth Doctor, have dramatically changed this understanding. It was revealed that the Doctor is actually the legendary “Timeless Child,” an alien being with an endless capacity for regeneration – and the original source of the Time Lords’ power to regenerate in the first place.
The show recently revealed that the Doctor has lived numerous lives before the one William Hartnell originally portrayed, the First Doctor, who took the TARDIS and left their home planet, Gallifrey. Jo Martin played one of these previous incarnations, known as the Fugitive Doctor, but many more existed even before the Time Lords themselves came into being – and we haven’t met them yet. While the details of regeneration have evolved over the years, October 29, 1966, remains a pivotal date because it was the first time this process was shown on television, making it a hugely important moment in Doctor Who history.
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2025-10-29 15:12