Alexander Balas (died 145 bc) was the king of Syria and Pergamum (Greek Asia Minor) and ruler of the remains of the Seleucid Empire (150–145 bc).
The pretended son of Antiochus IV Epiphanes, he won the Seleucid throne with the help of mercenaries, challenging and slaying Demetrius I Soter, the direct Seleucid heir. With the support of the Roman Senate and the Egyptian Ptolemaic dynasty, he ruled the remains of the Seleucid Empire until he was killed in battle against Demetrius II Nicator, son of Demetrius I Soter.
During his reign, Alexander pacified Palestine by naming Jonathan Maccabeus as Jewish governor but alienated the population by his revelry while feigning interest in politics and Stoic philosophy.