Uncle from Jackie Chan Adventures, he's hilarious, unpredictable and you just fall in love with him quickly.
Others would include...
Vergil, from Devil May Cry (if that's allowed?). Probably one of the best antiheroes you'll see. His character is amazing and his skills provide a great test for the player once they face off against him.
Rock Lee, from Naruto. He wasn't gifted with any kind of talent in fighting but that didn't stop him. Through hard work and determination he became the excellent ninja he wanted to be. He's proof for many that with enough effort, you can achieve whatever you put your mind to. He won me over very quickly.
Ace, from One Piece. Cool looking guy, cool powers. But there is much more to him than that. He's an excellent brother to Luffy and has a very deep, tragic past which makes you like the character even more and what he's become.
I actually cried a little when he died protecting his brother.