Back when John Tobias and Ed Boon were looking for a way to set their Jean-Claude Van Damme action game turned fighting franchise Mortal Kombat apart from Street Fighter II, they hit upon the idea of murder. Originally the idea was to be reserved for the final boss, Shang Tsung, alone, who would behead opponents who failed to beat him.
They quickly realized, though, that players would pay through the nose to perform graphic murders without the pesky side effects of corpse disposal or legal repercussion. Thus was born one of the staples of modern fighters, the fatality. Their inclusion in the original game sparked a controversy resulting in congressional hearings and the creation of a ratings board.
None of those things stopped the popularity of the fatality, though, and it has since moved far beyond Mortal Kombat and even past fighting games into things like God of War and first person shooters. That's not to say that every game did those things well. Some were downright ridiculous.