4. Harry Potter - Harry Potter and the Deathly Hallows Pt. 2
The Death: Harry (Daniel Radcliffe) finds out that he himself is the final Horcrux that must be destroyed to vanquish Voldemort (Ralph Fiennes), and so allows Voldy to cast the deadly Killing Curse upon him.
The Resurrection: However, Harry ends up in limbo, and after realising that Voldemort basically just destroyed part of himself, returns and kills Voldemort. Then everyone has kids and parades around in unconvincing middle-aged make-up.
Why He Should Have Stayed Dead: It's a cliche that the protagonist has to die a sacrificial death, but it really makes sense here; as Harry and Voldemort are essentially two sides of the same coin, it would have made for a far more affecting finale if Harry had to destroy himself to destroy his enemy. Furthermore, his death could have allowed Neville Longbottom to, as many had theorised before the final novel's release, reveal himself as the
real protagonist, and slay 'ol Voldy once and for all.