I'm usually against "older things have to be higher on the list" but Cartman and Spongebob seem a little high going against some of the most iconic cartoon characters in history. One hard thing, though, is that a lot of these characters are famous beyond their television show (Charlie Brown and Winnie the Pooh, for example). Are you putting any weight on the character being famous outside of the show (comic strips, books etc?), especially for stuff that happened before they were on television.
Well, I probably should base it on cartoons only. But it's hard to separate character achievements with different mediums. I think I got Charlie Brown about right and Winnie the Pooh is possibly too high, if we are trying to evaluate them as cartoon characters only. And how far do you think Cartman and Spongebob should drop?