Post a violent male character

Sento Oumi, the protagonist of Fight Ippatsu! Jūden-chan!!, has a terrible temper and tends to hit "magical" girls who annoy him with a baseball bat. Now, this could be seen as rather disturbing, but I figure we've seen enough angry anime girls beat up the guy for comedic affect. It's still cartoon violence. Feel terrible for the cute girls though, aww.

Not a toon for younger viewers though, since some of the female characters discover their own masochistic tendencies after getting hit with the bat.

Alucard from hellsing

Tatsumi from Akame ga Kill.

Just see the nice guy kill a girl after he learns about her torturing country people to death.

Accelerator from A Certain Magical Index.

Nothing meer violent than a man who will rip your balls off when pissed XD

Valtor in winx club. When he wants something he really means it.

Kenpachi Zaraki (Bleach)

Mondo Oowada

Jin Akutsu from Prince of Tennis. He is very violent as he's a delinquent, he also uses violence in tennis. He's also rumored as the Monster around the delinquents due to his strength and violence.