Memnoch
Lt. Vulture
It's part of the reason why I'm glad at times I've had limited exposure to other UK shows. It allows me to enjoy Doctor Who completely out of the loop of who they cast. Like with Billie Piper, no back ground and genuinely liked her (until RTD just couldn't let her alone). Another example is Catherine Tate, I absolutely LOVED her in seires 4 because I knew it wasn't going to be her "Catherine Tate Show" persona or the Donna we saw during Runaway Bride.