Who is Teiresias (from The Phoenician Women and The Bacchae) from Euripides V and what is their importance?

Teiresias is a blind prophet. In The Phoenician Women, Teiresias tells Creon that the only way to save Thebes is to sacrifice his son Menoeceus to appease the war god Ares.

In The Bacchae, Teiresias disguises himself as a bacchant in order to celebrate Dionysus and escape the god's wrath. He advises Pentheus to worship Dionysus as a god.