Doomguy. Generally whenever he enters a place, he makes damn sure that he's the last living creature that'll ever leave it. From
Doom.
Earthworm Jim. Has an awesome array of different ammo and loves finding opportunities to use it.
Link. For a kiddy Nintendo game character, Link sure does like waving that sword around.
Legend of Zelda.
Vivi Ornitier. The greatest threat to the world's ecosystem, he's never met an animal he didn't slaughter*. From
Final Fantasy IX.
*Obviously Moogles don't count.