This man killed a serpent at the Castalian Spring and ploughed dragon's teeth  to create the spartoi.  
One of this god's children became immortalized as "the white  goddess" Leucothea. Hyginus describes how he was turned into a  serpent in Illyria, a fate which also befell his wife as well. He is one of  two title figures in a novel by Roberto Calasso. This son of Telephassa  had his own wedding in a namesake structure, where all the gods were  in attendance. He was condemned for an "eternal year" to serve (*) Ares.  This man killed a serpent at the Castalian Spring and ploughed dragon's teeth  to create the spartoi.  This son of Agenor abandoned his search for Europa  when he was told to follow a cow and found a city where it became exhausted.  For 10 points, name this founder of Thebes.
One of this god's children became immortalized as "the white  goddess" Leucothea.
Cadmus