EUPATOR ū’ pə tôr (Gr. Εὐπάτωρ, of a noble father). The surname of the Seleucid Antiochus V (163-162 b.c.), who as a boy succeeded his father Antiochus IV Epiphanes (175-163 b.c.). He made peace with the Jews in the Maccabean period, but was betrayed and killed in 162 b.c.