10. “Time and the Rani”
Aside from being generally known as one of the all-time worst stories in Doctor Who history, "Time and the Rani" also boasts the most anticlimactic regeneration scene ever. Colin Baker, the Sixth Doctor, had been fired between seasons, and apparently wasn't even asked to come back to regenerate. This episode, which begins Season 24 of the classic series, begins with the TARDIS flying through space, being shot at with lasers by the Rani. It then cuts to Mel and the Sixth Doctor (new Doctor Sylvester McCoy in a wig) lying on the ground, apparently bothered by being blasted. The Doctor regenerates, and becomes the Seventh Doctor, but Mel is somehow perfectly fine a little while later. What? Easily the worst regeneration story ever.