We haven’t had a death in a while, so here’s a no-brainer. That is, at first glance. You see, Harry survived his duel with Voldy in the graveyard because their wands share the same core, initiating the Priori Incantatem enchantment.
(Don’t get me started on the weirdness of that idea. Really? Two wands, same core, and instead of exploding or merging or something ridiculously awesome, they just force each other to show the previous spells they cast? What are they, the NSA? I think it was all just a plot excuse to have Cedric and Harry’s parents’ ghosts talk to him, but it’s ridiculous. Though not quite as ridiculous as Moody/Crouch doing all sorts of elaborate plotting and manipulation of the Triwizard Tournament to get Harry into the graveyard. Why not just kidnap Harry and take him to Voldemort? He’s already supposed to be dead and buried at Azkaban and the real Moody was in a trunk, so who cares if his reputation is ruined by kidnapping The Boy Who Lived?)
Anyway. Neville used his father’s wand, which may or may not be true in my alternate universe. It really just depends on what happened to Neville’s parents. Did Voldemort kill them both? Was Frank or Alice Longbottom on duty for the Order or the Ministry at the time, and only one of them was killed? In any case, under ordinary circumstances, Neville wouldn’t have had the phoenix-core wand he would have needed to defend himself against Voldemort.
Or would he? Wands choose the wizard, and no doubt Harry’s holly wand chose Harry because it sensed he would need it against Voldemort. But would it have chosen Harry if Voldemort had not tried to kill him? Would it have chosen Neville instead? Also, would Cedric Diggory have died, or would he still be in that maze wondering what happened to Neville?
The mind boggles.