This is a Big Daddy, from the game Bioshock.
He protects the Little Sisters — mutated girls who have a certain resource you need in the game. You can see one to the right of him.
And here’s what it looks like when I try to fight him! Caution: this video contains scenes of violence, gore, and piss-poor gameplay.
I don’t know who bonzot, creator of the video, is, but my heart goes out to him. I, too, suck at dispatching Big Daddies.