1. The Gentlemen - Buffy The Vampire Slayer
This may be a surprise entrant in the number one slot, but I really feel as though this would make for a fantastic crossover. The Gentlemen are a group of pale, humanoid demons who constantly have creepy smiles on their faces and who roam the Buffyverse (or rather eerily float around it), going from town to town, seeking out the seven human hearts that they systematically require to stay alive. They're served by a group of demonic footmen in straight jackets. The sound of a human voice is fatal to the Gentlemen so, upon their arrival in a new town, they steal the voices of every inhabitant via the use of a magical box. This forces silence and has the added benefit of making their victims unable to scream for help as the Gentlemen cut their hearts from their still-living bodies. They made for, arguably,
the single best episode of
Buffy the Vampire Slayer in its seven season (and 144 episode) history, as the main characters were forced to go about saving the Gentlemen's potential victims without the aid of spoken communication. The Doctor is, of course, known for his funny one-liners and incredible wit, so to see an episode acted out in silence would be very, very interesting and a great new challenge for the Doctor to overcome. I can also just imagine the Doctor commenting on their snappy dress sense (if he could speak). Maybe he could write it on a post-it-note. When the Doctor got round to destroying the Gentlemen's magical box, it would be wonderful to watch him, quite literally, talk them to death.
Which villains from other TV shows do you think would make good enemies for the Doctor? Do you like the ideas in this list? Let us know in the comments below!