Introduction
Tyr is a Norse god associated with war, law, justice and the solemnity of oaths, best remembered for the courage and self-sacrifice he showed in helping the gods bind the monstrous wolf Fenrir, at the cost of his own hand.
This article follows Old Norse mythological tradition, chiefly the Poetic Edda and Snorri Sturluson's Prose Edda, noting where the two sources differ.
Family
Binding Fenrir
As the wolf Fenrir grew larger and more dangerous, the gods resolved to bind him, but he had already broken two previous chains with ease. They commissioned the dwarves to forge Gleipnir, a magical ribbon made from six impossible things (the sound of a cat's footfall, a woman's beard, a mountain's roots, a bear's sinews, a fish's breath and a bird's spittle), which appeared thin and harmless but could not be broken. Fenrir, suspicious of a trick, agreed to be bound only if one of the gods would place a hand in his mouth as a pledge of good faith. Only Tyr, known for his courage and honesty, was willing. When Fenrir found he could not break free, he bit off Tyr's hand.
Association with law
Tyr's willingness to make this sacrifice for the safety of all reflects his broader association with justice, oaths and the solemn keeping of agreements, even at great personal cost; his name is linguistically connected to the wider Indo-European sky-father god type and gives English the word "Tuesday" ("Tyr's day").
Parentage
Sources disagree on Tyr's father: the Prose Edda names Odin, while the Poetic Edda's Hymiskvida instead names the giant Hymir, a discrepancy that likely reflects different, only partially reconciled strands of the tradition rather than a single settled genealogy.