There's a folder for classic villains, but what about one for stories featuring classic companions? I mean to say, what if someone wrote a story where the Doctor popped over to visit Liz Shaw? That'd be good fun, and I reckon it would be well suited to the group.

I would think that most of the classic companions would be in fics with their respective Doctors. Or do you mean, e.g., the tenth Dr. Who popping back to visit Tegan Jovanka?

I guess that the companions could also go on their own adventures. I would pay good money to read a fic where Jo Grant stumbled into Equestria. I myself am turning over some ideas involving Jamie McCrimmon, as well as a few others...

(Does Iris Wildthyme count as a companion?)