Who was both a woman and a man at different times?

Hermes

Tiresias

Charybdis

Tityus

It's not in the answers but it should be Athena because in the Odyssey, she was a men (Mentor of Telemachus), and then she revealed her true form, becoming a woman again

Tiresias, he was born a man, but one of the things he was known for was being able to change from man to woman back to man in an endless cycle.