Tuesday is called after the Roman god Mars in Latin languages, e.g. Mardi in French, martedi in Italian- and dydd Mawrth and de Mart in Welsh and Irish Gaelic. In English, Swedish (tisdag) and Danish (Tirsdag), it is called after Tiw, one of the common Nordic and Anglo-Saxon deities. Tiw was the Anglo-Saxon form of Tiwaz
This god was variously known as Tiw, Tyr, Tiu, Tig, Teiw, Tiwaz, and numerous other variants according to Wikipedia
The son of Odin or the giant Hymir, according to whether the source is the poetic or prose Eddas, Tiw originally had attributes which were later taken by Thor and Odin. He may once have been the father of the gods (as Odin) and he was at one time the god of thunder, or may share some aspects of his identity with Thor. He was the god of single combat, heroism and justice. He is associated with death in several ways.
Tyr is known as "the leavings of the wolf" following a story in the Eddas. The gods tried to shackle the wolf Fenrisulfr (Fenrir) but could not succeed. The dwarves created a magical ribbon from things like a woman's beard and a mountain's roots. The wolf refused to be bound unless one of the gods put ha hand in the his mouth. Tyr did so. The other gods managed to bind the wolf and he will remain bound until the end of the world, Ragnorok. However, Fenrir bit off Tiw's hand in the course of the binding, hence Tiw was shown as one-handed in Norse mythology. According to Behind the name, Tyr will slay and be slain by the giant hound Garm, at Ragnarok.
A longer more detailed version of this story can be found on Focus on words. Many sources portray Tiw as the god of war, which makes a direct parallel with Mars, the Tuesday god in the Latin language countries. E.g Encyclopaedia Mythica refers to Tiw as "original Germanic god of war and the patron god of justice, the precursor of Odin."