Son-Goku, from DragonBallZ. He can be serisous at times, but otherwise, he's a full-blown idiot. He dies twice and leaves his family, once leaving and staying dead 4 seven years, not realizing his wife was pregnant with his second son. Yep, he's an idiot.
Vash the Stampede from Trigun. Considering his skills with firearms as well as his sheer stupidity, it's hard to tell whether he's an expert or a complete idiot.
However, at least he's stupid in a hilarious, funny way, which is partially why he's awesome.
