Superhero movies may typically be high-flying and filled with fast-paced action, but that doesn't mean they're always happy-go-lucky or triumphant and epic. Being a hero is not easy and oftentimes, their stories end in tragedy. This can lead to some of the best superhero movies having bittersweet or just genuinely sad endings. As sad as they can be, a depressing ending can actually end up making for some of the best superhero movie endings.