(ἀρχών), in Ancient History, the title of the highest magistrates at Athens. On the death of Codrus, about B.C. 1100, royalty was abolished at Athens, apparently because the ancient and venerable title of king (βασιλεύς) made the chief magistrate too independent of the nobles or eupatrids. Accordingly, although the highest magistracy remained hereditary in the family of Codrus, and was held for life, it was thought expedient to change its title into Archon, which simply signifies "a ruler." In point of fact, however, the archon's power was equal to that of a king, except that he was responsible to the nobles. The first archon was Medon, and the office remained hereditary in his family, thirteen members of which successively held it for life, until, in the year B.C. 752, the duration of the archonship was limited to ten years. But 38 years later, the exclusive right of the family of the Medontids was abolished, and the archonship thrown open to all the eupatrids without distinction. This, however, did not satisfy the nobles, as only few of them had a chance of being ever raised to the highest magistracy; and in order to increase this chance, another reform was effected in B.C. 683, by which the highest magistracy was divided among nine archons, whose office lasted only one year. The executive, which thus remained in the hands of the nobles, was now attainable to a large number of them in the course of a few years. But the abuse of their prerogatives led to reforms by which the archonship was ultimately thrown open to all the Athenian citizens indiscriminately.

The first of the nine magistrates was simply called the archon, sometimes with the epithet eponymous (ἐπονυμός), because the year was marked by his name, as it was at Rome by the names of the two consuls. At first this archon was at the head of the whole administration; but afterwards, during the period concerning which we have authentic information, and when democracy was fully developed, his functions appear to have been limited to the superintendence of the festivals of the Dionysia and Thargelia, and of the tragic choruses and certain sacrifices. All orphans were under his especial care; and he had, lastly, jurisdiction in all matters connected with the law of inheritance. His tribunal stood near the statues of the ten archgetae or eponymic heroes, not far from the agora, or place of the popular assemblies. The second archon bore the title of king (βασιλεύς); for as his functions embraced everything connected with the public worship of the gods, it would have been an act of impiety to alter his title: he was the king of the state so far as religion was concerned, just as the rex sacrorum was at Rome. He, in conjunction with his wife (βασιλεύσσα), had to perform certain sacrifices on behalf of the state, and he was especially intrusted with the superintendence of the mysteries, the festival of the Lenaea, the torch-races, and gymnastic contests. In all these matters the king-archon also had jurisdiction, and his court was in the stoa βασιλέως, near the agora. He had also to act the part of public prosecutor in all offences against religion, and against murderers whose case was judged by the Areopagus. But he himself had jurisdiction in disputes about the rights and duties of priests.

The third archon bore the title of polemarchus (πολεμάρχος), which indicates that originally he was the supreme commander of the Athenian forces; and in this capacity we find the polemarchus Callimachus at the head of the ten Athenian generals in the battle of Marathon, B.C. 490. But afterwards we no longer hear of the polemarchus as commander-in-chief; and his functions appear to have been limited to watching over the rights and duties of the resident aliens, just as the archon eponymus watched over those of the citizens; and arranging the funeral games in honour of those who had fallen in battle, and similar other public solemnities. His office was near the Lyceum.

Each of these three archons was entitled to appoint two assessors or assistants (προσκεποι), who, however, had to be sanctioned, after a previous scrutiny of their character and fitness, by the senate.

The six remaining archons were called thesmothete (θεσμοθέται), a name which is sometimes applied to the whole body of the archons. But the six formed a college of justice which had to take cognizance of all cases which did not belong to the jurisdiction of any other magistrate. They appointed the jury in the popular courts, and the days on which justice was administered. They had further to see that all new laws were duly entered, and annually to revise the laws to prevent contradictory enactments being maintained at the same time. They also superintended the voting in the popular assemblies, and ratified the treaties with foreign states. Their assessors were styled symbuli (συμβολοί).

From these accounts it is manifest that the functions of the archons were chiefly of a judicial nature; but the legislation of Draco, and still more that of Solon, produced considerable changes, for after the institution of the Ephorate and the popular courts, the archons, generally speaking, acted only as presidents in the various courts. In some cases, lastly, the whole college of the archons formed a court by itself; e.g., to pronounce the sentence of death against an exile returning to Athens contrary to law; to try magistrates deposed by the people; to conduct the elections of the ten generals and other military officers, and the like.

Until the time of Solon, the nobles alone were eligible to the archonship; his reforms threw open the office to all persons forming the highest property-class, whether they were eupatridae or demotae; and Aristides eventually opened up the highest magistracy to all Athenian citizens, without any qualification either of birth or of property. During the early or aristocratic period, the archons were elected, but when democracy attained its full development, they were chosen by lot; and to prevent the honour being thus conferred on unworthy persons, the newly-elected archons had to submit to a double scrutiny, one before the senate, which was termed ἀναξιόπουλος, and a second in the agora, which was called ὁσιοκαρδία. At these scrutinies they had to prove that their ancestors for three generations had been real Athenian citizens, and every archon was obliged to promise on oath scrupulously to observe the laws of the state. During their year of office all the archons were exempt from liturgies or extraordinary burdens, and any person insulting them was branded with infamy. At the expiration of their office they had to render an account of the manner in which they had discharged its duties, and when they were found blameless they became members of the high court of the Areopagus.

Even at the time when Greece had completely lost its political existence, the dignity of archon was sometimes an object of ambition with men of the highest rank, and the honour was sometimes even conferred upon, and accepted by, Roman emperors.

Archon is also applied by some authors to various officers, civil and religious, under the eastern or Greek empire.