For a show that covers literally everything that has happened (and ever will happen), Doctor Who is stuffed to the gills with untapped potential.
The Time Lord time-traveller can go wherever they want, whenever they want, meet whoever they want, and be home again before you can say "wibbly-wobbly".
With so much to do and see, things on the show do get forgotten about every now and then. This isn't usually a big problem, but sometimes viewers are left thinking "Hey, where did that really interesting storyline end up?" or "Whatever happened to that character I really liked?"
Over multiple decades, hundreds of episodes, lots of showrunners, and more TARDIS designs than you can shake a round thing at, Doctor Who's back catalogue is full of ideas that had all the promise in the world, but were not given the time and attention they deserved.
Any great TV show has its "What If?" moments, and Doctor Who is no exception - and it would be thrilling if any of these ten ideas made a comeback.
Don't put money on it, though.
10. Gwen’s Ancestry
Gwen Cooper is a no-nonsense, ass-kicking member of the Torchwood team in the popular Doctor Who spinoff. Originally a police officer, Gwen stumbles across Captain Jack Harkness and his gang, eventually joining them to fight those alien threats the Doctor doesn't get to.
However, this was not the first time Whovians had seen her face.
In the third episode of NuWho, the Ninth Doctor and Rose Tyler travel to Cardiff in 1869, where they encounter ghost-like aliens called the Gelth. Along the way they meet famed author Charles Dickens, and also bump into Gwyneth, a clairvoyant servant played by Eve Myles, who also plays Gwen Cooper in Torchwood.
This was actually addressed when the Tenth Doctor meets Gwen in Series 4. He deduces that she is from an old Cardiff family and, through something called "spatial genetic multiplicity", she has the same face as her ancestor.
While the showrunners could've done something with this, Gwen's connection to her psychic forebear is never mentioned again. What could've been an interesting storyline exploring the connection between Gwen and Gwyneth was instead a quick line to get around a case of double casting.