Which Greek hero is credited with founding Thebes?

Cadmus is the Greek hero traditionally credited with founding Thebes.

A prince of Phoenicia and son of King Agenor, Cadmus originally set out to find his sister Europa after Zeus carried her away. At Delphi, an oracle told him to abandon that search and follow a special cow. Where the cow finally lay down in Boeotia, Cadmus was instructed to establish a city.

Before he could complete the foundation sacrifice, a water-dragon sacred to Ares killed several of his companions. Cadmus slew the dragon and, following Athena’s instructions, sowed its teeth in the ground. Armed warriors called the Spartoi sprang from the soil. After they fought among themselves, five survivors helped build the city’s citadel, the Cadmeia.

Cadmus later married Harmonia, and their descendants included several major Theban figures, including Semele, the mother of Dionysus. The myth also links Cadmus with the introduction of the Phoenician alphabet to Greece, though that tradition is legendary and does not fit the historical chronology of Greek writing.