Who is Tiresias?

Tiresias was a blind prophet of Apollo who appears in the Odyssey, the works of Pindar, and many Greek dramas. He was a son of the nymph Chariclo, had a very long lifespan, and was noted for his great prophetic gifts, especially understanding of the language of birds, interpretation of smoke patterns, and ability to communicate with the dead. He is associated with the city of Thebes and played an important role in Sophocles's Theban plays.
In the Odyssey, he appears in Book XI, which describes Odysseus's journey to the Underworld. Tiresias warns Odysseus to ensure that his men do not harm the cattle of Helios and foretells many of the future adventures of Odysseus. He also explains how to attract and converse with other spirits by offering them blood.