youngest daughter of the Macedonian king Ptolemy XII Auletes of Egypt, sister of Cleopatra VII (Cleopatra) and the kings Ptolemy XIII and XIV. During the Alexandrian war, Arsinoe attempted to lead the native forces against Cleopatra, who had allied herself with Julius Caesar (Caesar, Julius).

Upon landing in Alexandria in 48, Caesar captured the members of the Ptolemaic royal family, but Arsinoe managed to escape with the aid of Ganymedes, her mentor, and joined the Egyptian army headed by Achillas. Following a feud between Ganymedes and the Egyptian commander, Arsinoe ordered Achillas executed. Ganymedes pressed Caesar's forces hard and negotiated an exchange of Arsinoe for Ptolemy XIII, but the Romans, with reinforcements, defeated the Egyptian army, and Arsinoe was sent to Rome to be led in Caesar's triumph. After this humiliation Arsinoe found sanctuary in the Temple of Artemis at Ephesus, in Asia Minor, for she feared her ambitious sister; Cleopatra, after securing the affections of the Roman triumvir Mark Antony, in 41 persuaded him to execute Arsinoe.