I just saw an ad for an anime called One Punch Man which appears to combine this with a regular superhero in the form of a guy who fights monsters as a hobby
While I absolutely love the manga, after reading it you'll see it doesn't really match the thread.
As a DM, I deal with character death by cheering and giving a fist pump, or maybe a V-for-victory sign. I would also pat myself on the back, but I can't really reach around like that.