(Εὐλαῖος), an eunuch, became one of the regents of Egypt and guardians of Ptolemy Philometor on the death of Cleopatra, the mother of the latter, in B. C. 173. The young king was then 13 years old, and he is said to have been brought up in the greatest luxury and effeminacy by Eulaeus, who hoped to render his own influence permanent by the corruption and consequent weakness of Ptolemy. It was Eulaeus who, by refusing the claims of Antiochus IV. (Epiphanes) to the provinces of Coele-Syria and Palestine, involved Egypt in the disastrous war with Syria in B. C. 171. (Plb. 28.16; Diod. Fragm. lib. xxx. Exc. de Leg. xviii. p. 624, de Virt. ct Vit. p. 579; Liv. 42.29, 45.11, 12; App. Syr. 66; Just. 34.2.)