
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.