Archon (Gr. ἄρχων, pl. ἄρχοντες) is a Greek word that means "ruler" or "lord," frequently used as the title of a specific public office. It is the masculine present participle of the verb stem ἀρχ-, meaning "to rule," derived from the same root as monarch.
In ancient Greece the chief magistrate in various Greek city states was called Archon. The term was also used throughout Greek history in a more general sense, ranging from "club leader" to "master of the tables" at syssitia.
In Athens a republican system of nine concurrent Archons evolved, led by three respective remits over the civic, military, and religious affairs of the state: the three office holders being known as the Eponymos archon (Ἐπώνυμος ἄρχων; the "name" ruler, who gave his name to the year in which he held office), the Polemarch ("war ruler"), and the ArchonBasileus ("king ruler"). The six others were the Thesmothétai, Judicial Officers. Originally these offices were filled from the wealthier classes by elections every ten years. During this period the eponymous Archon was the chief magistrate, the Polemarch was the head of the armed forces, and the Archon Basileus was responsible for some civic religious arrangements, and for the supervision of some major trials in the law courts. After 683 BC the offices were held for only a single year, and the year was named after the Archōn Epōnymos. (Many ancient calendar systems did not number their years consecutively.)
After 487 BC the archonships were assigned by lot to any citizen and the Polemarch's military duties were taken over by new class of generals known as stratēgoí. The ten stratēgoí (one per tribe) were elected, and the office of Polemarch was rotated among them on a daily basis. The Polemarch thereafter had only minor religious duties, and the titular headship over the strategoi. The Archon Eponymos remained the titular head of state under democracy, though of much reduced political importance. The Archons were assisted by "junior" archons, called Thesmothétai (Θεσμοθέται "Institutors"). After 457 BC ex-archons were automatically enrolled as life members of the Areopagus, though that assembly was no longer extremely important politically at that time. (See Archons of Athens.)