(Θήρων), tyrant of Agrigentum in Sicily, was the son of Aenesidemus, and descended from one of the most illustrious families in his native city. According to Pindar, they traced their descent from Cadmus, but his more immediate ancestors were Rhodians who had been among the colonists that founded Gela; and his great grandfather Telemachus had distinguished himself as a leader of the revolution which overthrew the power of Phalaris. (Pind. Ol. ii. iii.; and Schol. ad loc.) It is therefore certain that Theron inherited a leading place among his countrymen of Agrigentum, but of the steps by which he rose to the sovereign power we have no accurate information. Polyaenus indeed tells us (6.51), that having been appointed by the state to superintend the erection of some extensive public buildings, he applied the money furnished him for this purpose to his own objects, and raised a body of mercenary guards, by whose assistance he established himself on the throne. Whatever credit be due to this story, we learn that he had assumed the government of his native city as early as B. C. 488, and retained it from that time, without interruption, till his death. (Diod. 11.53.) It is probably to the early period of his rule that we may refer the attempt of his kinsmen Capys and Hippocrates to overthrow his power, which was frustrated by their defeat at the river Himera. (Schol. ad Pind. O. 2.173.) The next event of which we find mention is his expulsion of Terillus from Himera [TERILLUS], which took place probably as early as B. C. 482. (Hdt. 7.165.) While he by this means united Himera to his own dominions, and thus ruled over two of the most powerful cities of Sicily, he was in close alliance with Gelon, ruler of Syracuse and Gela, to whom he had given his daughter Demarete in marriage. (Schol. ad Pind. Ol. II. init.) Their combined strength was soon called forth to resist the formidable Carthaginian armament under Hamilcar which landed in Sicily in B. C. 480, with the professed object of restoring Terillus. Theron himself had occupied Himera with a large force, but terrified at the magnitude of the Carthaginian army, he shut himself up within the walls of the city, and sent to Gelon for assistance. In the great victory which followed, the Syracusan king appears to have borne by far the greatest part [GELON]; but Theron derived a large share of its advantages, and was not only left in undisputed possession of Himera, but received so large a number of prisoners as his share of the spoil, that by employing these in public works at (Agrigentum, he raised that city to an unprecedented state of grandeur and magnificence. (Diod. xi 20-25.)

His friendly relations with Syracuse continued unaltered until the death of Gelon, B. C. 478 : but on that event the disputes between Hieron and his brother Polyzelus brought about a rupture between the former and Theron. Polyzelus had married Demarete, the widow of Gelon, and thus succeeded to the connection of the latter with the Agrigentine prince : in addition to which it appears that Theron himself was married to a daughter of Polyzelus : hence when the latter was driven into exile by the jealousy and intrigues of Hieron [POLYZELUS], he naturally sought refuge at the court of Theron. That monarch espoused his cause, and raised an army for the purpose of reinstating him, but hostilities were prevented, and a peace concluded between the two sovereigns. According to Timaeus, this was effected by the mediation of Simonides, who prevailed on Theron to give his sister in marriage to Hieron. Diodorus, on the contrary, relates that the citizens of Himera, who were oppressed by the government of Thrasydaeus, the son of Theron, having made overtures for assistance to Hieron, the latter betrayed their application to Theron, and induced him in return for this benefit to abandon the cause of his brother Polyzelus. (Timaeus apud Schol. ad Pind. Ol. 2.1, 29, 37 ; 11.48.) Theron had been much alarmed at the threatened revolt of Himera, and he now proceeded to establish his power in that city by the greatest severities against the disaffected party, many of whom he put to death, while he drove others into banishment. Having thus gradually thinned the population of the city, he repeopled it with settlers from all quarters, but especially of Dorian origin. (Diod. 11.48, 49.) From this period Theron appears to have reigned without dispute over both Agrigentum and Himera until his death in B. C. 472 : and notwithstanding his cruelties towards the Himeraeans, he is praised for the general mildness and equity of his government. It is certain that Agrigentum enjoyed great prosperity under his rule, and that it was then adorned not only with splendid buildings, but with public works of a more useful character, such as reservoirs and conduits for water on a most stupendous scale. (Diod. 11.25.) Like his contemporary rulers at Syracuse, he also displayed much favour towards artists and poets, and the victories he obtained at the Olympic games were immortalised by Pindar. The praises of the poet are confirmed by the more impartial testimony of Diodorus. (Pind. Ol. ii. iii.; Diod. 11.3, x. Exc. Vales. p. 558.) A magnificent monument was erected to him in the neighbourhood of Agrigentum, at which heroic honours were paid to his memory. (Diod. l.c. and 13.86.)