Ptolemaeus (Greek: Πτολεμαῖος; 201 BC – 130 BC) was initially the satrap of Commagene, later becoming its first king in 163 BC. He belonged to the Orontid dynasty, founded by Orontes I. Ptolemaeus' father was King Orontes IV of Armenia, son of Arsames I.

Ptolemaeus was the last satrap (governor) of the state of Commagene, a province in the Seleucid Empire. He served under the Syrian Greek kings Antiochus III the Great, Seleucus IV Philopator, Antiochus IV Epiphanes and Antiochus V Eupator.

Ptolemaeus served as Satrap of Commagene until 163 BC. When the Seleucid Empire began to disintegrate, Ptolemaeus asserted his sovereignty and made Commagene an independent kingdom in 163 BC.^[1] Ptolemaeus declared Samosata, the capital of Commagene under the Seleucid rule, as the capital of his new kingdom.^[1]

Ptolemaeus was a relative to King Mithridates I of Parthia. Also, according to fragments of inscribed reliefs found at Mount Nemrut, archaeologists have discovered that Ptolemaeus was a descendant of King Darius I of Persia. Ptolemaeus died in 130 BC and his wife is unknown. His son and successor was Sames II Theosebes Dikaios.