A senator and close friend of Cicero; tribune 63 BC, praetor c. 59, governor of Asia and then Cilicia, and a committed Pompeian in the civil war who was later pardoned by Caesar through Cicero's intercession. In Fam. 13.70 Cicero, citing his intimate friendship with Balbus, recommends Balbus's freedman T. Ampius Menander to the proconsul P. Servilius.