Fan Casting Kid Hero in Sort by Tropes

They'll fight off hordes of monsters with techniques the likes of which master swordsmen would never equal. They'll wield weapons spoken of only in the oldest of legends. They'll Save the World and everyone in it from destruction five times over. And they'll do all of this while not even being old enough to drive. The Kid Hero is, as the name implies, a child, a teenager, a young adult. The exact age varies up and down the scale, from 8 to 17, 18 or 19, but they're never an adult by whatever the local standards are. The "base age" seems to be between 10 and 15, 16, 17, 18 or thereabouts, though their numeric age may not be revealed.