S. Walker and P. Higgs (eds.), Cleopatra of Egypt, The British Museum, London, 2001, p. 244, where it is mentioned in the note for no. 266 which has been identified as a portrait of Mark Antony.
S. Walker op. cit., "...surviving portraits of Antony are notably inconsistant, and it is difficult to sustain an individual identification without hair. A helmeted head recently sold on the art market is markedly similar, though made of one block of marble and apparently of Augustan date...".
Mark Antony (83-30 B.C.) was a Roman general and politician who formed the Second Triumvirate together with Octavian and Marcus Aemilius Ledidus, after the assasination of Julius Caesar in 44 B.C. Octavian remained in Rome, Lepidus governed over Hispania and Africa, and Antony the East. Married five times, his fourth wife was Octavian's sister Octavia, but his last wife, possibly the most famous, was Cleopatra VII of Egypt, the former lover of Julius Caesar, by whom he had three children. In 33 B.C. the Triumvirate broke apart and civil war ensued between Antony and Octavian. Antony was defeated at the battle of Actium in 31 B.C., and committed suicide by falling on his sword in 30 B.C.. Cleopatra was permitted to carry out his funeral rites after she had been captured by Octavian, and herself committed suicide later that year.