Nomarchs (Ancient Egyptian: heri-tep a'a) were the semi-feudal rulers of Ancient Egyptian provinces. Serving as provincial governors, they each held authority over one of the 42 nomes (Egyptian: sepat) into which the country was divided. Nome is derived from the Greek nomos, meaning a province or district, and nomarch is derived from the Greek title nomarches (νομάρχης), the ruler of a nomos. The nomarchs exercised considerable power.
The division of the kingdom into nomes can be documented as far back as the Old Kingdom (in the 3rd millennium BCE) and continued even up until the Roman period.
The title was also in use in modern Greece for the heads of the prefectures of Greece, which were also titled nomos (pl. νομοί, nomoi; νομαρχία, nomarchia also being used to refer to the area under a nomarch's purview).