Classic Doctor Who: The 10 Timey-Wimiest Episodes

This special story features both the Second and Sixth Doctors beign drawn to the same time and place by time travel experiments being conducted by an unethical scientist. They get involved in an adventure featuring the Androgums—a race that are slaves to their physical appetites.

Unusually, the story goes to great lengths to show how events in a past Doctors’ life affect his future self. When the Second Doctor is subjected to a process which starts to turn him into an Androgum, the Sixth Doctor feels the effects, and must work all the harder to help defeat their enemies.

Like in many other episodes on this list, these concepts are not fully explored in the story, but have become raw material for much future discussion about time travel and the impact of changing history in the Doctor Who universe, both in spin-off media and in the series itself.