Trierarch (, triērarchos) was the title of officers who commanded a trireme (triēres) in the classical Greek world. In Athens and a few other states this officer was also required to pay for the outfitting and maintenance of the ship. Trierarchs thus had to be men of considerable means, since the expenses incurred could run as high as a talent in the course of a year. By the late 4th century BC, trierarchs in Athens often shared responsibility for a single ship, as the financial burden of the job had become too great.