This post contains spoilers for War of the Worlds (the original HG Wells book and the more recent movie adaptation starring Tom Cruise)
I like heroes. I like seeing heroes defeat the villain and save the day. Nothing makes me happier when reading a book or watching a movie than seeing how the protagonist overcomes the challenge at the climax.
It stands to reason, then, that I am usually disappointed when a story ends with someone other than the hero saving the day. This isn't to say I think the main character should accomplish everything on their own, without any help. Quite the contrary, I love supporting characters who can stand on their own and contribute to the plot. But the eventual triumph, the key act or choice, should, I feel, come down to the protagonist.
Those feelings aside, it's a generally accepted rule of fiction that a random outside force should never be the source of the hero's victory. Deus ex machina is widely regarded as a terrible way to resolve the conflict in a story.
So it's strange to me that HG Wells, one of the most well-regarded authors in western literature, resorted to it for his War of the Worlds. It's not clever planning, a desperate strike, or the abilities of a singular individual that stops the alien invasion, it's microbes. Specifically, microbes that humans have long since become immune to, but the aliens have never encountered. So, they die from the resulting infection.
Essentially, mankind is saved because the aliens were stupid. No matter what the protagonist does in the course of the story, the aliens will always die and humanity will be spared because the alien invaders didn't develop basic quarantine methods. While this fits with the themes of the book, the idea of being lost and helpless amid utter chaos, the everyman's quest for survival rather than the noble hero's daring endevours, its a risky chance to take. People expect to see the hero take on a challenge and come through. This is worth remembering wen writing yourself. Always make sure to have the hero defeat the villain through wits, strength, skill, or determination. Resist the temptation to invent an easy answer to get a problem out of the way.
You know, in the Tom Cruise version of War of the Worlds, after his character's son disappears, believed dead, only to re-appear in the very last scene, revealing he survived the invasion, I always liked to think that the son had this amazing, awesome adventure kicking alien ass and maybe even setting off the chain of events that led to the aliens' defeat, while his dad and sister spent the next hour not doing much at all.
Do you guys have any other examples where the hero isn't the one to overcome the final challenge