What game does William Afton die in?

In Five Nights at Freddy’s 3. He returns as the main antagonist as Springtrap, the suit inside of which he was trapped and killed.

Does William Afton ever die?

They promptly took control of the Funtime animatronics and attacked Afton, but when he managed to fend them off and prepared to kill the boy, they used the fused endoskeleton to grab William. Unable to escape, the endoskeletons dragged him into a nearby furnace along with them, killing him for good.