Arsinoe III (246 BC or 245 BC - 204 BC) was Queen of Egypt ( 220 - 204 BC. She was a daughter of Ptolemy III and Berenice II.
Between late October and early November, 220 BC she was married to her brother, Ptolemy IV. They ruled jointly for sixteen years. In Summer, 204 BC she was murdered in a palace coup, shortly before her husband's own death.