Heracles was the greatest of the Hellenic chthonic heroes, yet unlike other Greek heroes no historical tomb was identified as his. He represented the closest Greek approach to a demi-god, an ambiguous figure honored at the same festivals both as a hero, with chthonic offerings poured into the ground, and as an Olympian god.

Walter Burkert traced the deep core of his mythology to a Neolithic hunter culture and to shamanistic crossing-of-the-threshold traditions, which would account for his exploits at the edges of the world and his journey into the realm of the dead. The question of whether Heracles was originally a hero or a god was already debated in antiquity, and his dual cult preserves both answers at once.

The festival of the Heracleia, commemorating the hero's death, was held on the second day of the month Metageitnion (roughly late July to early August). Worship of Heracles is attested across the Greek world from at least the 6th century BCE, with early evidence in inscriptions from Phaleron near Athens. Many cities maintained two separate sanctuaries, honoring him in one as a god and in the other as a hero.

Heracles was the patron of gymnasia and of military training, and a protector of men and especially of youths and ephebes. His cult spread by local absorption and, later, by imperial patronage, notably among the Macedonian royal house, which claimed descent from him. After the 4th century BCE he was widely identified with the Phoenician god Melqart.

Heracles was famed for his immense strength, but he also used his wits when force alone did not suffice. His standard attributes in art and literature were the lion skin and the club. He was portrayed as a playful, benevolent figure who made the world safe for humanity by ridding it of monsters, yet capable of cold and terrible vengeance against his enemies. Euripides depicted him as driven by forces beyond rational control, and Seneca attributed his madness to a refusal of ordinary life in favor of the extravagant violence of the heroic existence.

Ancient descriptions of his appearance vary. Dicaearchus described him as square-built, muscular, dark-skinned and hook-nosed, with brownish-amber eyes; Pseudo-Apollodorus said his body measured four cubits with fire flashing from his eyes; Pindar called him short of stature but dauntless of soul. In art he is typically shown with short curly hair, a thick neck, broad shoulders and heavily developed musculature, as in the famous Farnese Hercules.

Birth and childhood. Hera's hatred sprang from Heracles being the illegitimate son of Zeus by the mortal Alcmene. Zeus prolonged a single night into three while disguised as her husband Amphitryon, and Alcmene conceived twins of different fathers: the divine Heracles and the mortal Iphicles, later father of Heracles's charioteer Iolaus. Hera manipulated the timing of births so that Eurystheus would be born first and gain the kingship destined for a descendant of Perseus. According to one tradition Alcmene exposed the infant out of fear of Hera, but Athena brought him to Hera, who nursed him unwittingly; when he suckled too strongly her milk sprayed across the sky and formed the Milky Way. At eight months old the twins were attacked by two serpents sent by Hera: Iphicles cried out in terror while Heracles strangled both snakes with his bare hands.

Youth. As a boy Heracles killed his music teacher Linus with a lyre, and Amphitryon sent him to tend cattle in the countryside. The sophist Prodicus composed the allegory known as the Choice of Heracles, preserved in Xenophon's Memorabilia, in which the personifications Vice and Virtue offered him a life of easy pleasure or one of severe glory, and he chose the path of virtue. He later married Megara, daughter of Creon of Thebes.

The Twelve Labours. After Hera drove him mad and he killed his children (and in some versions Megara), the Oracle of Delphi ordered him to serve King Eurystheus and perform the tasks set for him. Eurystheus assigned ten labours and, refusing to count two, added two more, for a total of twelve: to slay the Nemean Lion; to slay the Lernaean Hydra; to capture the Ceryneian Hind; to capture the Erymanthian Boar; to clean the Augean Stables in a single day; to slay the Stymphalian Birds; to capture the Cretan Bull; to steal the man-eating Mares of Diomedes; to obtain the belt of the Amazon queen Hippolyta; to obtain the cattle of the monster Geryon; to steal the golden Apples of the Hesperides; and to capture Cerberus, the guardian of the underworld.

Further adventures. Beyond the labours Heracles wooed Iole, won an archery contest for her hand but was refused, and in renewed madness killed her brother Iphitus. As penance, by order of the Delphic Oracle, he was sold into a year's servitude to Queen Omphale of Lydia, where he was made to do women's work while she wore his lion skin and carried his club. Among many other exploits he rescued Prometheus by shooting the eagle that tormented him; sacked Troy after King Laomedon cheated him of his promised reward, sparing only Podarces, who was renamed Priam; rescued Alcestis by wrestling Death at her grave; and slew the giant Antaeus by lifting him from the earth that renewed his strength.

Death and godhood. Heracles won Deianira as his wife after defeating the river god Achelous. The centaur Nessus, mortally wounded by Heracles for attempting to assault her, gave Deianira his blood as a supposed love charm. Years later, fearing a rival in Iole, she smeared it on a tunic for Heracles; the Hydra venom in it burned through his flesh. In agony he built a pyre on Mount Oeta and was burned, his mortal part consumed while his divine part ascended. Through Zeus's will he was apotheosized, reconciled with Hera, and married her daughter Hebe on Olympus, with whom he had the sons Alexiares and Anicetus.

Heracles had many female consorts. His marriages were to Megara, daughter of Creon of Thebes; to Omphale of Lydia during his servitude; to Deianira, whose unwitting use of the poisoned tunic caused his death; and finally, after his deification, to the goddess Hebe. His most famous affair was with the fifty daughters of King Thespius, all of whom he was said to have lain with, an exploit sometimes called his Thirteenth Labour, from whose sons many royal lines claimed descent.

Many tales also gave Heracles male lovers, a development connected with the rise of Greek pederasty; Plutarch claimed his male loves were beyond counting. The most closely linked was Iolaus, his Theban charioteer and squire, at whose Theban tomb male couples were said to swear oaths of loyalty. Others named in ancient sources include Hylas, who sailed with him on the Argo before being carried off by water nymphs; Abderus, devoured by the Mares of Diomedes and honored with the founding of Abdera; and Elacatas, who gave his name to a Spartan sanctuary and games.

Heracles's marriages and nearly all of his affairs produced numerous children, including many sons and at least four daughters. The most prominent was Hyllus, son of Heracles by Deianira (or by Melite), whose descendants were known as the Heracleidae.

The Heracleidae are remembered for their long struggle to return to the Peloponnese after Eurystheus drove them out, a tradition that linked the legendary descendants of Heracles to the later Dorian peoples of Greece. The children he had with Megara, by contrast, are best known for their tragic death at his own hands during his Hera-induced madness.

In Rome and the modern West, Heracles is known as Hercules. The Romans adopted his myths largely unchanged and incorporated his exploits into their own legends, including episodes set in Italy such as his defeat of the monster Cacus, which became part of the foundation lore of Rome.

Beyond the Greco-Roman world Heracles was widely identified with foreign deities. He was equated with the Egyptian god whom the Greeks understood through their own Heracles, and from the 4th century BCE onward closely assimilated to the Phoenician and Canaanite god Melqart, a process that helped spread his cult across the Mediterranean.

The fame of Heracles made his name, and that of his Roman counterpart Hercules, a recurring element in later geography, dynasty and culture. Ruling houses such as the Macedonian and Spartan royal families claimed descent from him as Heracleidae, lending their kingship the prestige of his lineage.

His name and image persisted long after antiquity, attached to constellations, place-names, and countless works of art and literature, so that Heracles or Hercules became one of the most enduring and widely recognized figures of classical mythology.