Ptolemy IV Philopator was the fourth pharaoh of Ptolemaic Egypt from 221 to 204 BC.
Ptolemy IV was the son of Ptolemy III and Berenice II. His succession to the throne was accompanied by a wide-ranging purge of the Ptolemaic royal family, which left control of the realm's government largely in the hands of his courtiers Sosibius and Agathocles. His reign was marked by the Fourth Syrian War with the Seleucid empire, which culminated in a decisive Ptolemaic victory at the Battle of Raphia, one of the largest battles of the whole Hellenistic Age. In the final years of his rule, control over the southern portion of the country was lost to the rebel pharaoh Hugronaphor. Ptolemy IV died in mysterious circumstances in 204 BC and was succeeded by his young son Ptolemy V Epiphanes under the regency of Sosibius and Agathocles.
In ancient sources, Ptolemy IV was criticised for being more interested in luxury and court ceremony than government, politics, and foreign relations. The decline of the Ptolemaic dynasty is usually traced to his reign.