Difficult. If it's got to be a character...well, I could cop out and say "someone played by Charlotte Coleman", but...that would be a cop-out. (And anyway, who? Possibly Lisa Lyons - she was intelligent and cheerful and fun, but on the other hand I'd probably fall foul of her dad and her brother...)
So instead, I'll say Ace from Doctor Who, on the grounds that I used to have a fair bit of a crush on her.
