Tostig (tŏsˈtĭg) [key], d. 1066, earl of Northumbria; son of Earl Godwin of Wessex. He was banished with his father in 1051 and returned with him in their armed invasion of 1052. Made earl of Northumbria in 1055, Tostig jointly invaded (1063) Wales with his brother Harold (later King Harold of England). The Northumbrians revolted against Tostig's severe rule in 1065 and chose Morcar, brother of the earl of Mercia, to be their earl. Tostig fled to Flanders. The next year he raided the English coast, then joined the Norwegian king Harold III in defeating Morcar. Tostig and his ally were killed by Tostig's brother Harold at Stamford Bridge.