For HP, I play a wide variety of characters: Sirius Black (post-Azkaban), Lily Evans, Luna Lovegood, Neville Longbottom, Severus Snape, Fred Weasley, Ginny Weasley, name-only types from all houses. I've done all of the Trio, too, but it's been a while.
For Sherlock, I play both John and Sherlock. I can do Mycroft and Lestrade, but they're better as secondary than primary characters.