Trierarch (Greek:τριήραρχος,romanized: triērarchos) was the title of officers who commanded atrireme (triēres) in theclassical Greek world.
InClassical Athens, the title was associated with thetrierarchy (τριηραρχία,triērarchia), one of the public offices orliturgies, which were filled by wealthy citizens for a year. As the name implies, the trierarch was responsible for the outfitting and crewing of a trireme, and for commanding it in battle. Trierarchs thus had to be men of considerable means, since the expenses incurred could run as high as atalent in the course of a year. As the cost of the office was great, co-trierarchs (syntriērarchoi) were also appointed. By the 4th century BC, trierarchies in Athens were assumed by navy boards (symmoriai), as the financial burden of the job had become too great.