Germanic sky god and god of war. He also played a role as a god of justice. Originally Tiwaz. Tiw was the Anglo-Saxon name. The name is believed to derive from the same root as the Greek Zeus, the Roman deus, and the Sanskrit deva. Roman writers equated him with their Mars. Thus the third day of the week, which the Romans had named after Mars, came to be known in English as Tuesday ("Tiw's day").
Although Tiw played a major part in the religion of the continental Germans, he played only a minor role in Norse mythology as recorded by the Icelandic writers. His role seems gradually to have been usurped by the god Wodan/Odin. In the Prose Edda of Snorri Sturluson it was Tiw (Tyr) who placed his hand in the mouth of the wolf Fenrir as a guarantee that the gods meant no harm when they bound him with the fetter Gleipnir. When the gods refused to loose Fenrir, the wolf bit off Tiw's hand. Tiw thus became the "one-handed god". According to Snorri, the wolf Garm was to kill Tiw at Ragnarok.