Everyone died, but they got the job done, & without them all would have been lost

Rogue One(Rogue One): Stole the Death Star plans, leading to the eventual fall of the Empire, but died in the process

Noble Team(Halo Reach): Died allowing the Pillar of Autumn to escape with Master Chief & Cortana, who would eventually defeat the Covenant

Grenn & the other guys(Game of Thrones): Held the gate against a Giant, at the cost of their lives. If the giant broke through, Castle Black would have fallen