(Εὔαρχος), tyrant of the Acarnanian town of Astacus in the first year of the Peloponnesian war, B. C. 431, was ejected by the Athenians in the summer and reinstated in the winter by the Corinthians. (Thuc. 1.30, 33.) Nothing is mentioned further either of him or of Astacus, but it is probable that the Athenian interest was soon restored. (Comp. 1.102.)