Brutus, also called Brute of Troy, is a legendary descendant of the Trojan hero Aeneas, known in medieval British legend as the eponymous founder and first king of Britain. This legend first appears in the Historia Brittonum, an anonymous 9th-century historical compilation to which commentary was added by Nennius, but is best known from the account given by the 12th-century chronicler Geoffrey of Monmouth in his Historia Regum Britanniae.
Some have suggested that attributing the origin of 'Britain' to the Latin 'Brutus' may be ultimately derived from Isidore of Seville's popular 7th-century work Etymologiae (c. 560–636), in which it was speculated that the name of Britain comes from bruti, on the basis that the Britons were, in the eyes of that author, brutes, or savages. A more detailed story, set before the foundation of Rome, follows, in which Brutus is the grandson or great grandson of Aeneas – a legend that was perhaps inspired by Isidore's spurious etymology and blends it with the Christian, pseudo-historical, "Frankish Table of Nations" tradition that emerged in the early medieval European scholarly world (actually of 6th-century AD Byzantine origin, and not Frankish, according to historian Walter Goffart) and attempted to trace the peoples of the known world (as well as legendary figures, such as the Trojan house of Aeneas) back to biblical ancestors.
Supposedly following Roman sources such as Livy and Virgil, the Historia tells how Aeneas settled in Italy after the Trojan War, and how his son Ascanius founded Alba Longa, one of the precursors of Rome. Ascanius married, and his wife became pregnant. In a variant version, the father is Silvius, who is identified as either the second son of Aeneas, previously mentioned in the Historia, or as the son of Ascanius. A magician, asked to predict the child's future, said it would be a boy and that he would be the bravest and most beloved in Italy. Enraged, Ascanius had the magician put to death. The mother died in childbirth.