abstract:Lagus (Greek Λάγος; lived 4th century BC) from Eordaea was the father, or reputed father, of Ptolemy, the founder of the Ptolemaic dynasty. He married Arsinoe, a concubine of Philip II, king of Macedon, who was said to have been pregnant at the time of their marriage, on which account it is told that the Macedonians generally looked upon Ptolemy as in reality the son of Philip; but it is possible that this is a later myth fabricated to glorify the Ptolemaic dynasty.