How many brothers did thor the god of thunder have?

Thor is actually Odin's only son by the earth-spirit Fjorgyn, so while he has many half-brothers, he shares a mother with no one. Baldur and Vali are confirmed in Skaldic poetry as sons of Odin, though Snorri Sturluson attests vali as a child of Loki. Sturluson names Tyr a son of Odin in the Prose Edda, but a son of Hymir in the Poetic Edda. Hodr and Vithar are most likely sons of Odin, given their roles in the events of Ragnarok.