The undeniable fact remains that Leon is just one man. He is a very capable killer, but what if were facing something bigger than him? If a bad-ass band of survivors (think the residents of Escape from New York, because in an apocalypse, they will) descends upon the group, Leon cannot snipe them all and Dr Schultzs brand of diplomacy is unlikely to cut any ice. What can President Marshall do? Thats right. Call in the big guns. And a fist of red granite. Hellboy is a character that can be floored by no-one. Rage zombies? No problem (assuming that the virus cannot transmit to creatures of hell, otherwise that would be quite a serious problem). Cannibals? Hellboy laughs in the face of cannibals. And rabid dogs. And pretty much any threat that you care to think of.