Tyr was the sky god in Norse mythology. He sacrificed one of his hands for the good of the gods. In Asgard, the land of the gods, there was a demonic wolf called Fenrir. He was so huge and fierce that only Tyr would dare to approach him. The gods decided to tie the wolf up, using an unbreakable chain forged by dwarfs.
The wolf, wanting proof that the chain was harmless, asked that one of the gods put a hand in his mouth as the chain was slipped on. The beast was disappointed to find the chain could not be broken. Tyr had sacrificed his hand so that the gods could feel safer. Odin took Tyr's place as Sky god around the eighth and ninth centuries.