Famous soothsayer from Thebes who was blind after he had seen Athena take a bath. He was first and foremost Oedipus advisor. It was the shadow of the dead Tiresias that Odysseus consulted.
According to another myth Tiresias was once out on a walk, when he saw to snakes mating. He sat there watching for hours, when the snakes sensed his presence. Since they did not want to be disturbed, they attacked him. Tiresias managed to kill the female, and at the same moment he killed her, he turned into a woman.
As a woman Tiresias became a prostitute of great fame for seven years. Then, one day, the episode with the snake was repeated, but this time Tiresias killed the male, and so turned back into a man.
When Zeus and Hera had a disagreement on which sex enjoys the most pleasure during intercourse they decided to let Tiresias judge, since he had experienced both. Hera insisted men enjoy sex more, while Zeus claimed the opposite. Tiresias then said, that if sexual pleasure could be put on a scale from one to ten, then men were at one, and women at three times three.
This angered Hera so much she blinded Tiresias, but Zeus gave him inner sight (wisdom and the ability to see the future) and extended his life with seven generations.