Gaius Antonius Hybrida (lived 1st century BC) was an Ancient Rome politician.

Gaius was the second son of Marcus Antonius Orator and brother of Marcus Antonius Creticus, being thus uncle of the notorious Mark Antony. His military career started as a legate and cavalry commander of Lucius Cornelius Sulla during the Mithradatic Wars . After Sulla's return to Rome, Gaius Antonius remained in Greece with a force of cavalry. He was supposed to maintain peace and order but ended in plundering the countryside and sacking for his own profit several temples and holy places. Rumours of atrocties committed on the local population, which included maiming and torture, earned him the nickname Hybrida ("Cruel").

In 76 BC he was tried for his malpractices, but escaped punishment due to bribery and the weight of the Antonius family backing him. Years later he was removed from the senate and stripped out of senatorial rank by the censors, still on charges due to the atrocities committed in Greece. Soon afterwards, Hybrida was reinstated and decided to start his political career again. In spite of his bad reputation, was elected tribune in 71 BC, praetor in 66 BC, and consul with Marcus Tullius Cicero in 63 BC. He secretly supported Catiline, but Cicero won him to his side by promising governership of the rich province of Macedonia. On the outbreak of the Catilinarian conspiracy, Antonius was obliged as consul to lead an army into Etruria, but handed over the command on e day of battle to Marcus Petreius, on the ground of ill-health.

In Macedonia, he made himself so detested by his oppressive rule and extortions over the people, that he was forced to leave the province. In 59 BC, Antonius was accused in Rome both of having taken part in the Catiline conspiracy and of extortion in his province. Despite Cicero's defense, Antonius was condemned, and went into exile at Cephallenia. He seems to have been recalled by Julius Caesar, since he was present at a meeting of the Senate in 44 BC, and was censor in 42 BC.

His daughter Antonia Hybrida was the first wife of Mark Antony.

Cicero, In Cat. iii. 6, pro Flacco, 38; Plutarch, Cicero, 12; Dio Issius xxxvii. 39, 40; xxxviii. 10. On h~s trial see article in Paulyissowa s Realencyclopadse.