20 Years Later, This ‘Doctor Who’ Two-Part Story Has Never Been Topped

Doctor Who might be on indefinite hiatus right now, but if the timey-wimey history of the world's longest-running sci-fi show has taught us anything, it's that the Doctor always finds a way to regenerate. The flagship BBC franchise has survived for over 60 years because its primary characters can be seamlessly recast, a built-in narrative reset button used to reinvent the show without starting over. Since no iteration of the Doctor or a companion lasts long-term, exit stories are a mainstay of the series, delivering action-packed and emotionally charged episodes to mark the end of their journey.