Son of the Phoenician king Agenor and brother to Europa. When Zeus kidnapped her, Cadmus was told by his father to find her and not return if he didn't.
Cadmus, not being able to find his sister, consulted the oracle at Delphi, who said he must abandon the search and in stead follow a cow and found a city where the animal lay down to rest. Thus, he became the founder of Thebes. He killed a dragon near Thebes and planted its teeth in the ground. Out of the teeth warriors grew, and they fought each other until only five remained. Cadmus made these five warriors, the sparti (the sown), head of Thebes noble families. One of them, Echion, he eventually married to his daughter Agave.
In killing the dragon Cadmus had upset Ares, the dragon's master or father, and had to serve him for eight years to make penance. When he finished, he married Ares and Aphrodite's daughter Harmonia. The couple had four daughters: Autonoe, Ino, Semele and Agave, and a son: Polydoros.
Cadmus ended his days in Illyria after a series of misfortunes, and he and Harmonia were transformed into snakes. It was Cadmus who gave the Greeks the greek alphabet.