Raboot The Admirer:My most obvious choice for a fat celebrity would be Jack Black. On top of finding him attractive, he's just so charismatic and full of energy! I also liked the Actor Bud Spencer, for similar reasons.
For a more obscure one... There's a spanish rock singer called Kutxi Romero. He basically has everything I physically like in a man. Plus I appreciate his chest-showing habits.

I completely agree with you on Jack Black! He's such a fun and weird (in an amazing way) guy who isn't afraid to be himself!