Rhea Silvia

She was the only child of Numitor, king of Alba Longa. When Numitor's brother Amulius ousted him and assumed the throne he forced Rhea Silvia to become a Vestal Virgin, thereby insuring, he thought, that there would be no other to claim the throne he had usurped. But Mars happened upon her in his sacred grove, and raped her. She gave birth to the twins Romulus and Remus. Some myths have her being drowned in the Tiber when her sons were cast adrift.