(Ἀλκέτας), the brother of PERDICCAS and son of Orontes, is first mentioned as one of Alexander's generals in his Indian expedition. (Arrian, 4.27.) On the death of Alexander, he espoused his brother's party, and, at his orders, murdered in B. C. 322 Cyane, the half-sister of Alexander the Great, when she wished to marry her daughter Eurydice to Philip Arrhidaeus. (Dioed. 19.52; Polyaen. 8.60; Arrian, apud Phot. p. 70, ed. Bekker.) At the time of Perdiccas' murder in Egypt in 321, Alcetas was with Eumenes in Asia Minor engaged against Crateris; and the army of Perdiccas, which had revolted from him and joined Ptolemy, condemned Alcetas and all the partizans of his brother to death. The war against Alcetas, who had now left Eumenes and united his forces with those of Attalus, was entrusted to Antigonus. Alcetas and Attalus were defeated in Pisidia in 320, and Alcetas retreated to Termessus. He was surrendered by the elder inhabituants to Antigonus, and, to avoid falling into his hands alive, slew himself. (Diod. 18.29, 37, 44_46; Justin, 13.6, 8; Arrian, apud Phot. l.c.)