Archon, Greek Archōn, in ancient Greece, the chief magistrate or magistrates in many city-states. The office became prominent in the Archaic period, when the kings (basileis) were being superseded by aristocrats.
At Athens the list of annual archons begins with 682 bc. By the middle of the 7th century bc, executive power was in the hands of nine archons, who shared the religious, military, and judicial functions once discharged by the king alone. The archon proper was the principal civil and judicial officer and may have presided over both Boule (Greek boulē, council) and Ecclesia (Greek ekklēsia, assembly); as eponymous archon, he gave his name to his year of office.
Next came the polemarch, commander in war and judge in litigation involving foreigners. Third, the kingship survived in the basileus, who, as chief religious officer, presided over the Areopagus (aristocratic council) when it sat as a homicide court. Lastly there were six thesmotetai (“determiners of custom”), who dealt with miscellaneous judicial problems.
The potential power of the archons placed them under a variety of restrictions. Before entering office they had to undergo an examination (dokimasia) by the Boule and the law courts of birth qualifications, physical fitness, treatment of parents, and military activity; at the end of their term, they underwent an examination (euthyna) of their conduct, especially financial, while in office. Membership was originally open only to nobles by birth (eupatrids or eupatridai), who served as archons for life. The term of office was eventually reduced to 10 years, then to a single year, after which, since they could not be reelected, the archons became life members of the Areopagus. The eupatrid monopoly was broken c. 594 bc, when Solon made the top or top two property classes eligible for office.
Under the Cleisthenic constitution (508–c. 487), archons were elected directly by the Ecclesia; later they were chosen by lot from 500 previously elected candidates. Until 457 the office was still restricted to the top two classes. Then eligibility was first extended to the third property class; finally the fourth class was admitted in fact, though theoretically ineligible.
In the 5th century the authority of the archons declined. The polemarch lost his army command to 10 tribal commanders (stratēgoi), who also replaced the archons in the administrative sphere. The archons thus became primarily judicial officers. By the mid-5th century they no longer gave their own judgments but merely conducted preliminary inquiries (anakrisis), then brought the case before a jury, presiding over the hearing, but with no responsibility for directing the jury on matters of law.
Archons were also found at Delphi, Plataea, Phocis, and eastern and western Locris. During the 5th century the institution spread widely in the Aegean islands, mainly under Athenian influence, and then in the Hellenistic period to Anatolia.