Doctor Who has been telling stories about a time traveling adventurer since 1963, but in the program’s original iteration, time travel itself was rarely part of the plot. Normally, the Doctor’s time machine, the TARDIS, was used simply as a means to get the cast to the setting of their next adventure. Once the monster or megalomaniac of the day was defeated, the Doctor and his companions would be on their way.
When the series was revived in 2005, the tone was different. Frequently time travel, time manipulation, alternate timelines and the rest were an integral part of the story. This was especially true when writer Steven Moffat was involved. His script for the celebrated episode "Blink" even coined a phrase for these sorts of shenanigans: timey-wimey.
But Steven Moffat didn’t invent the idea of time-travel goofiness in Doctor Who, he simply popularized it. Indeed, over the 26 seasons of the original series' run, one can find more than a few examples of where temporal mechanics were part of the fun.
Here are ten of the most significant...
10. The Ark (1966)
The Ark does
something novel at the time--it takes place in two separate time frames. The TARDIS arrives on a giant space ark carrying humanity away from a planetary disaster, accompanied by nearly enslaved aliens known as Monoids. The Doctor's visit prompts a deadly disease to spread through both races, but after two episodes the Doctor puts things right and is on his way again.
But then we get the twist: the TARDIS returns to the ark hundreds of years later to find the political situation has reversed—humans are now enslaved to the Monoids. The Doctor now has to save humanity and help both races forge a future together.