What are some アニメ where the main character is a badass?

Hmm.... Well, I'm not sure what あなた define "badass" as, but Code Geass has a pretty awesome lead. The guy can command people to die without blinking and take on an entire nation's military with only a ragtag team of rebels, a スーパーナチュラル power that he's still learning about, and a chess board. I dunno about you, but Lelouch is a pretty badass character if あなた ask me. ^^

Guts from Berserk is probably the most badass アニメ character that I've seen

Hei (Darker Than Black)

Vash - Trigun

Medaka Box with Medaka Kurokami.

孫 悟空 from Dragon Ball Z has to be one of the most badass main characters i have ever seen