In Harry Potter and the Deathly Hallows, Part 1, Harry and company are in Malfoy manner's cellar. Peter Pettigrew walks down and then pretty stupidly walks into the cellar without looking, where he is stunned:
After that, he just disappears from the movie and doesn't reappear, not even at the Battle of Hogwarts. What happens to him? Did the stunning spell actually kill him somehow? Or did Voldemort just kill him off-screen?