The Iron Knuckle is an adversary in the Zelda series of video games, first appearing in The Adventure of Link, and is one of the toughest sub-bosses Link will have to defeat. It swings a mighty axe that deals devastating blows to whatever comes in its way. If Link is hit by this axe, he will lose quite a large amount of life energy. In Ocarina of Time, Iron Knuckles are associated with the Gerudo. Though quite similar to Dark Nuts, Iron Knuckles are empty shells powered by evil, whereas Dark Nuts have a physical body.