Gaius Antonius, younger son of Marcus Antonius the orator, and uncle of Mark Antony. He was a colleague of Cicero during the latter's praetorship (66 BC) and consulship (65). Appointed governor of Macedonia in 62, he returned to Rome in 59, when he was charged with implication in the Catiline conspiracy and extortion in his province. Defended by Cicero, he was condemned and went into exile. Recalled probably by Caesar, he was censor in 42 BC.
Side note: Mark Antony also had a brother named Gaius, Antonius who was the governor of Macedonia in 44 BC. In 43 he was taken prisoner by Marcus Junius Brutus, who put him to death in the following year.