Antonius (fem. Antonia) was the nomen of the gens Antonia, one of the most important plebeian (meaning not patrician) families of ancient Rome. The family claimed descendancy from Anton, a son of the god Hercules. Women of the family carried the name Antonia, according to the Roman naming convention. The Antonii produced several important Roman generals and politicians, listed bellow.

• Mark Antony (83 - 30 BC), ally of Julius Caesar, Triumvir and afterwards enemy of Caesar Augustus. Probably the most famous Antonius, his life is depicted in William Shakespeare's play Antony and Cleopatra

Other Antonii

• Gaius Antonius (died 42 BC)
• Gaius Antonius Hybrida, Mark Antony's uncle
• Lucius Antonius, Mark Antony's brother
• Marcus Antonius Creticus, Mark Antony's father
• Marcus Antonius Orator (died 87 BC)

Women

• Julia Antonia
• Antonia Major
• Antonia Minor

Others

• lex Antonia
• Emperors Gordian I, Gordian II and Gordian III were also members of the Antonius family, although not directly related to the Republic protagonists cited above.