an eunuch, the guardian of the young king Ptolemy, and the regent of the kingdom, recommended the assassination of Pompey, when the latter fled for refuge to Egypt after the loss of the battle of Pharsalia in B. C. 48 (Lucan, 8.484, &c.). He plotted against Caesar when he came to Alexandria, later the same year. It was Pothinus who placed Achillas over the Egyptian forces, with directions to seize a favourable opportunity for attacking Caesar, but he himself remained with the young king in the quarters of Caesar. But as he was here detected in carrying on a treasonable correspondence with Achillas, he was put to death by order of Caesar. (Caes. Civ. 3.108, 112; D. C. 42.36, 39; Plut. Cues. 48, 49; Lucan, 10.333, &100.515, &c.)