Antiochus V Eupator (Greek: Αντίοχος Ε' Ευπάτωρ, whose epithet means "of a good father"; ca. 172 BC – 161 BC) was a ruler of the Greek Seleucid Empire who reigned 163–161 BC (based on dates from 1 Maccabees 6:16 and 7:1).

Antiochus V was only nine years old when he succeeded to the kingship, following the death in Persia of his father Antiochus IV Epiphanes and his mother Laodice IV. The general Lysias, who had been left in charge of Syria by Epiphanes, served as regent for the child, although he was challenged by other generals. The Roman Senate still kept Demetrius, son of Seleucus IV and the rightful heir to the throne, as hostage, refusing to release him because they considered it better to have Syria nominally ruled by a boy and his regent than the 22-year-old Demetrius.

At the outset of the reign of Antiochus V, there was an attempt by the Syrians to quell the Maccabean Revolt in Judea, but this ended in a weak compromise. After a military victory in the Battle of Beth-Zecharia, and the killing of Eleazar, a brother of Judas Maccabaeus, Lysias was informed that Philip, (a confidant of Antiochus IV Epiphanes, who had accompanied this previous king to conquer Mesopotamia, and had been entrusted prior to the death of the king with the upbringing of Antiochus V), was returning to the capital with the other half of the Seleucid army. Lysias felt threatened, and advised Antiochus V to offer peace to the Jews. The Jews accepted, however, in order to ensure they would not rise against them soon again, the Syrian king and regent broke their promise and tore down the walls of Jerusalem before leaving.