Topping the list are Fred and George Weasley from the Harry Potter series. They can make even the worst of times hilarious. These two can definitely make me bowl over with laughter.
I like Sean Dillon from the James Patterson novels. Daring, cunning and with overflowing sense of humor and self-depracation.
Dumbledore, because he is the epitome of politeness & humility amidst his own greatness.
Mandy (from the cartoon series, "The Grim Adventures of Billy and Mandy) -- she never smiles, always obnoxious, cunning, sarcastic, but, it's cartoon, so what the heck, I like her.
LOTR's Samwise Gamgee. It was more because of him that the One Ring was destroyed. His loyalty and bravery made him come back for Frodo.
I like Gil Grissom's character from CSI. He's the only one who can make me feel guilty crushing bugs!
Agatha Christie's Hercule Poirot. He makes me laugh with his use of English idioms. And who could ever forget his "little grey cells"?
I also like Temperance of the Bones series. She is so smart, yet so naive. Her atheism is not in the least offensive when she voice it out, coming from her, it was matter of fact, almost naive.
Willy Wonka (but I'm influence more by Johnny Depp's portrayal than the book character).
A lot more but for the time being, I guess these will do.