Pope Joan
The Pope Joan story states that she was German and arrived in Rome dressed in men's clothes, managing to convince people that she was in fact a man. Her alleged male name was John Anglicus. She started out in the clergy as a curiae notary; next she became a cardinal, and then finally she became the Pope. She served as pope  for about two and a half years but her true gender was exposed when she became pregnant. The birth of her child was thought to have taken place either on the road that separated the Colosseum and St. Clement's or in the church. Her death and punishment are unknown.