Helen (ancient Greek: Ἑλένη), sometimes known as Helen of Troy or Helen of Sparta, is a character in Greek mythology whose name has the meaning of "tea" or "torch".  Almost all mythographers classics allude to its myth. She was considered the daughter of Zeus and claimed by many heroes due to her great beauty. She was seduced or kidnapped by Paris, prince of Troy, which originated the Trojan War.
Zeus, transformed into a swan, seduced Leda and lay with her the same night as Tindáreo, husband of Leda and king of Sparta. As a consequence, Leda laid two eggs; from one were born the sons of Zeus, Helena and Pollux, both immortal, and from the other the sons of Tindáreo, Clytemnestra and Castor, mortal. In any case, Castor and Pollux were considered twins and were known as Dioscuri. Other sisters of Helena were Timandra and Filónoe.
Another tradition said that Helena was born from the union of Nemesis and Zeus, transformed respectively into a goose and a swan. The egg that Nemesis laid was found by a shepherd who gave it to Leda. Helena was born from the egg and Leda cared for her as if she were her true mother.  Hesiod, on the other hand, alleges that Helena is the daughter of Zeus and an unnamed Oceanid. 
In the sanctuary of the Leucipids of Sparta there was an egg hung from the ceiling and supported by ribbons. This was believed to be the one in which Leda had given birth. 
Abduction of Helen by Theseus and Pirithous
Helena was recognized for her beauty since she was a child. One day, while she was participating dancing in a sacrifice in the sanctuary of Artemis Ortia de Esparta, she was surprised and kidnapped by the Athenian hero Theseus in the company of her friend Pirítoo. After capturing her, they drew lots for her maiden, corresponding to Theseus. But when Theseus returned to Athens, the Athenian people did not allow the girl to enter the city, which is why Theseus led her to Aphidna, along with her mother Etra hers. Next, Theseus and Pirítoo decided to march to Hades to kidnap Persephone with the intention of making her the consort of Pirítoo. During the stay in Hades of Theseus and Pirítoo, the Dioscuri rescued Helena. In turn, they took Theseus's mother and Pirítoo's sister as prisoners, who led them to Sparta to make them Helen's slaves.    
There is a tradition that says that Helena and Theseus had Iphigenia as their daughter, but that, when Helena was released by her brothers, she decided to give her daughter to her sister Clytemnestra, who was already married to Agamemnon.  But the legend The most widespread point out that Iphigenia was a natural daughter of Clytemnestra.
Wedding with Menelaus
When Helena reached the age of marriage, she had many suitors who flocked from all over Greece, encouraged by the fame of her great beauty and because she and her future husband would reign in Sparta. Tindáreo, fearing to provoke a war between the rejected suitors, followed a advice of Odysseus. In return, he promised him his help to get his niece Penelope as his wife.
Odysseus's advice consisted in taking from the suitors the oath to abide by the decision that was made about who would be Helena's husband and the obligation to come to the aid of the chosen one if at any time his wife were seduced or kidnapped. After taking the oath, Tindáreo chose as Helena's husband Menelaus, brother of Agamemnon, king of Mycenae, who was married to his other daughter, Clytemnestra. In other versions, it was Helena herself who chose Menelaus.
Menelaus and Helena had a daughter, Hermíone and according to some authors, also a son, Nicóstrato.  
Rapture or seduction of Paris
The goddess Aphrodite had promised Helena's love to the Trojan prince Paris as a prize for having decided in her favor in the beauty contest that had confronted her