Who is Cadmus (from The Bacchae) from Euripides V and what is their importance?

Cadmus is the founder of Thebes and Pentheus' father. At the start of the play, Cadmus joins Teiresias in dressing as bacchants to honor Dionysus as a god. His grandson, however, will not follow his urgings and pay tribute to Dionysus. Cadmus finds his grandson's body after he is killed by the women of Thebes, while they are under the influence of Dionysus. Cadmus also attempts to honor the god, Dionysus, who condemns Cadmus and his wife to become serpents and lead foreign armies around Greece, attacking the cities.