Helen of Troy is a legendary heroine, that took part of the legendary Troyan Cycle (Troyan war that would have happened in the 12th or 11th century BC ).
In the greek mythology she was the daughter of the god Zeus and Leda, a mortal woman. She was once considered to be the most beautiful woman in all of Greece. She was so beautiful that a war was started in the hopes of winning her hand in marriage. There is an old saying that Helen was the woman with a "face that launched a thousand ships".
She was married to the king of Sparta, Menelaos, but she eloped with the troyan prince Paris, begining a conflict that would bring ruin to Troy.