10 Best One-Time Only Doctor Who Villains

Doctor Who's "monster of the week" format means that the show cycles through a massive amount of villains with each passing series.

While some episodes bring back old favourites from the classic and modern eras, most stories include a brand-new villainous threat for the Doctor to humiliate and ultimately defeat, and with the show having put out hundreds of episodes since 1963, there are a lot of bad guys that exist within this universe.

But with a limited amount of screentime available - there are only around ten stories per series, after all - the vast majority of evildoers will probably never return for another onscreen appearance. This means that Doctor Who history is littered with villains who only popped up in one adventure, never to do battle with the Doctor again.

While they're not all great (let's just forget about the Kandyman and the Abzorbaloff, shall we?) this vast group of one-hit wonder baddies does contain a few gems: some truly incredible villains who left an indelible mark on the show in a brief amount of time. Even if they never return, we'll always remember them with great fondness.

The Gelth are among the most underrated baddies in Who's modern era.

Appearing for the first and only time in the Ninth Doctor episode The Unquiet Dead, the most intriguing thing about them is that they're not technically villains, a layer that makes them an interesting creature to use as the story's de facto antagonists.

Appearing like blue, gaseous ghosts, the Gelth are actually a humanoid species who have suffered a great deal. After losing their bodies during the Time War, they're essentially seeking refuge in this episode, and their only desire is to inhabit human bodies and take a physical form once again.

So when they start possessing corpses (and start attacking Rose with said corpses), and when billions of Gelth try to squeeze through the rift and take the Earth by force, they're acting from a place of desperation. We won't go as far as saying they're relatable (we can't speak for anyone else, but we've never lost our bodies during a Time War) but we understand why they felt like they needed to act in a villainous way.

It's rare for a Doctor Who villain to have such a compelling motivation. Plus, their blue ghostly forms gave them a really cool, mesmerising look too.