This is the final boss of the game, and completely unmissable, just keep playing and you'll reach this point.
In addition if you aren't powerful enough to beat him, you might want to retreat from the fight try to collect other trophies then come back for a round two. You can collect gold bolts, powerup your guns and come back. He is one of the harder bosses for the game, but with powered up weapons he won't be that hard.