10 Classic Doctor Who Enemies Who Need To Return
9. Fenric
Fenric is one of the Doctor's most interesting enemies, coming from the beginning of the universe itself. The two had been locked in a cosmic game of wits for centuries, until the Doctor defeated Fenric and imprisoned him off-screen. Yet despite this, this entity has only appeared in a single televised story, The Curse of Fenric - the penultimate story of the classic era. That story is highly regarded as one of the best of the Seventh Doctor's run, with deep and mature themes and some intense moments between the Doctor and his companion, Ace.
Fenric is a powerful enemy who is discovered to be responsible for events in Ace's past, making him a very modern sort of villain. However, the most interesting aspect of the Doctor's relationship with Fenric is the idea that the two of them have been locked this cosmic game of chess for centuries, with Ace being an unwitting pawn. The fact that the Doctor has to break Ace's faith in him in order to defeat Fenric is so diabolically brilliant and it leads to some devastating scenes.
It would make perfect sense for Fenric to return, manipulating events from the shadows in order to orchestrate a rematch. It could make for an amazing season arc, with the Doctor being unknowingly caught up in a subtle game, gradually turning to manipulate the people around them, including their companions. There's so much potential for some dark and psychological storytelling that would fit modern sensibilities perfectly.