In Greek mythology, Iolaus was a Theban hero, celebrated as the charioteer, squire and faithful companion of Heracles, whom he assisted in several of the Labours. The son of Heracles' twin brother Iphicles, he was also numbered among the Argonauts. He is best remembered for cauterizing the necks of the Lernaean Hydra so the severed heads could not regrow, and in later tradition he led colonists to Sardinia, where he was honored with a hero cult and athletic festival at Thebes.
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I.Family
Iolaus was the son of Iphicles, the twin brother of Heracles, and Automedusa, daughter of King Alcathous of Megara. As the son of Heracles' brother, he was the hero's nephew as well as his close companion.
According to Plutarch, Heracles gave his own wife Megara to Iolaus when she was thirty-three and he was sixteen. The couple had a daughter, Leipephilene (a name whose accuracy is disputed among scholars), and through her line Iolaus was connected to the legendary kings of Corinth.
II.Mythology
Relationship with Heracles: Iolaus often acted as Heracles' charioteer and companion throughout his adventures. Plutarch recorded that male lovers would pledge faith and exchange vows of affection at Iolaus' tomb, noting that he was "beloved" by Heracles — a tradition connected to the cultural ideals associated with the Sacred Band of Thebes.
Adventures: Iolaus gave essential help to Heracles during the second Labour, the battle against the Lernaean Hydra, by searing each neck with firebrands after Heracles severed the heads, so that they could not grow back. According to Diodorus Siculus, Heracles later sent Iolaus to Sardinia together with nine of his sons to colonize the island, founding the people known as the Iolei. The colonists were said to have been buried on Sardinia, where their tombs became renowned as oracles.
III.Legacy
A gymnasium at Thebes was named after Iolaus and stood near his tomb. The annual Heracleia festival held there came to be known as the Iolaea, featuring gymnastic and equestrian contests in which victors were crowned with garlands of myrtle.
His name survives in modern nomenclature: a genus of Lycaenid butterflies bears the name Iolaus, and an exoplanet orbiting the star HAT-P-42 was named after him through the International Astronomical Union's NameExoWorlds initiative.