Alexander Balas (i.e. "lord"), ruler of the Greek Seleucid kingdom 150-146 BC, was a native of Smyrna of humble origin, but gave himself out to be the son of Antiochus IV Epiphanes and heir to the Seleucid throne.

His claims were recognized by the Roman senate, Ptolemy Philometor of Egypt and others. He marrier Cleopatra Thea, a daughter of the Ptolemaic dynasty. At first unsuccessful, Alexander finally defeated the reigning king Demetrius I Soter in 150 BC. Being now undisputed master of the empire, he abandoned himself to a life of debauchery.

Demetrius Soter's son profited by the opportunity to regain the throne. Ptolemy Philometor, who was Alexander's father-in-law, went over to his side, and Alexander was defeated in a pitched battle near Antioch in Syria.

He fled for refuge to a Nabataean prince, who murdered him and sent his head to Ptolemy, who had been mortally wounded in the engagement.

See 1 Maccab. 10 ff.; Justin xxxv. 1 and 2; Josephus, Antiq. xiii. 2; Appian, Sir. 67; Polybius xxxiii. 14.