Roman surname of the Junian gens. Its association with betrayal traces to Marcus Junius Brutus (c. 85 B.C.E.-42 B.C.E.), Roman statesman and general and conspirator against Caesar. The Brutus (Anglicized as Brute) who was the mythological eponymous founder of Britain in medieval legend was said to be a descendant of Aeneas the Trojan.

Others are reading

Definitions of Brutus from WordNet

Brutus (n.)
statesman of ancient Rome who (with Cassius) led a conspiracy to assassinate Julius Caesar (85-42 BC);
Synonyms: Marcus Junius Brutus