Alcetas (Greek Ἀλκέτας; died 320 BC), was the brother of Perdiccas and the son of Orontes from Orestis. He is first mentioned as one of Alexander the Great's generals in his Indian expedition.
On the death of Alexander, Alcetas espoused his brother's party, and, at his orders, murdered Cynane in 322 BC – the half-sister of Alexander the Great – when she wished to marry off her daughter Eurydice to Philip Arrhidaeus, the nominal king of Macedon.
At the time of Perdiccas' murder in Egypt in 321 BC, Alcetas was with Eumenes in Asia Minor engaged against Craterus; 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 waged by Alexander's general Antigonus. Alcetas and Attalus were defeated in Pisidia in 320, and Alcetas retreated to Termessus. He was surrendered by the city elders to Antigonus, and, to avoid falling into his hands alive, killed himself.
This article incorporates text from a publication now in the public domain: Smith, William, ed. (1870). "". Dictionary of Greek and Roman Biography and Mythology.