1. A king of Illyria, who was in all probability a son of Pleuratus, and younger brother of Agron, both of them kings of that country (see Schweighaüser, l.c.). He is first mentioned shortly after the death of Agron, as commanding a force sent by Teuta, the widow of that monarch, against Epeirus, B. C. 230. He advanced through the passes of Atintania, defeated an army which the Epeirots opposed to him, and penetrated as far as Phoenice, when he was recalled by Teuta to oppose the Dardanians (Plb. 2.5, 6). At this time he was clearly in a private station, and the period at which he assumed the sovereignty is uncertain; but it seems probable that, after the defeat and abdication of Teuta (B. C. 229), Scerdilaidas succeeded to a portion of her dominions, though at first without the title of king, which he probably did not assume till after the death of his nephew Pinnes, on whom the Romans had bestowed the sovereignty, under the guardianship of Demetrius of Pharos (see Schweighäuser, ad Polyb. l.c.). In B. C. 220 we find him joining with Demetrius in a predatory expedition against the Achaeans, and concluding a treaty with the Aetolians against that people : but he quickly became dissatisfied with the conduct of his new allies, and was, in consequence, induced by Philip to change sides, and conclude an alliance with the Macedonian monarch (Plb. 4.16, 29). In the spring of 218 he sent a small squadron to the support of Philip, but he appears to have rendered him little efficient assistance, either on that or any subsequent occasion during the war. Notwithstanding this he claimed from the Macedonian king his promised share of the booty, and conceiving himself aggrieved in this respect, in the following year (B. C. 217) he turned his arms against Philip, captured by treachery some of his ships, and made an inroad into Macedonia itself, where he made himself master of some of the frontier towns. Philip, who was at this time in the Peloponnese, hastened to the relief of his own dominions. and having quickly recovered the places he bad lost, occupied himself during the winter in the equipment of a powerful fleet, to carry on operations against the Illyrian king. Scerdilaidas, alarmed at these tidings, applied for assistance to the Romans, who were favourably disposed towards him from jealousy of Philip, but were too hard pressed at home to furnish him any effectual succour. They, however, in the summer of B. C. 216, sent a squadron of ten ships to his support, and the very name of a Roman fleet struck such a terror into Philip that he abandoned the Adriatic, and retired, with his whole fleet, to Cephallenia (Plb. 5.3, 95, 101, 108, 110). But during the following years his Roman allies were able to give little assistance to the Illyrian king, and Philip wrested from him the important fortress of Lissus, as well as a considerable part of his dominions. In B. C. 211 Scerdilaiidas joined the alliance of the Aetolians with the Romans, but his part in the war which followed appears to have been confined to threatening and infesting the Macedonian frontiers by occasional predatory incursions (Liv. 26.24, 27.30, 28.5; Plb. 10.41). It would appear that he must have died before the peace of 204, as his name, which is coupled with that of his son Pleuratus, during the negotiations in B. C. 208, does not appear in the treaty concluded by P. Sempronius with the Macedonian king (see Liv. 27.30, 29.12). He left a son, PLEURATUS, who succeeded him on the throne.