One of the children resulting in the union between Leda and Zeus. She was kidnapped when she by two Athenians when she was a child by two Athenians, Theseus and Pirithous, in their quest to each marry a daughter of Zeus. They failed, and were captured by Hades when they ventured to the underworld to steal Persephone from her husband Hades. Her brothers, together know as the Dioscuri, rescued her and razed Aphidnae, the city in which she was held captive.
When Helen returned to Sparta, many suitors approached Tyndareus for her hand. One of the suitors, Odysseus, came up with the idea that all suitors would agree to ally themselves with the chosen husband if anyone should quarrel against the chosen one. Tyndareus supported the idea and supported Odysseus' courting of Penelope.
Tyndareus chose Menelaus to marry Helen. Menelaus did not even go to Sparta to court her, but sent his brother Agamemnon instead. He would later marry Clytemnestra, Helen's half sister. Menelaus became King of Sparta after Tyndareus died.
Paris, a prince of Troy, was bribed with promises by the goddesses Hera, Athena, and Aphrodite as he was asked to decide which was the fairest. He chose Aphrodite, and Helen was the reward. He went to Sparta, and took her to Troy with him. Menelaus called upon the promises made by Helen's suitors, nearly all of Greece's most powerful and influential men, and they sailed to Troy ("The Face that Launched 1000 ships" - Christopher Marlowe), thus begining the Trojan War. Homer's The Illiad documents the ten year Trojan War, and the destruction of the city resulting from Helen and Paris' union.
There are differing versions of Paris and Helen's feelings about each other. Some contend she loved him (thanks to Aphrodite), others that Helen craved chaos, hated Paris, and used him as a tool to bring about the war.
She married Paris' brother, Deiphobus, after Paris died. Then returned to Sparta with Menelaus after he killed Deiphobus. She was later exiled by her own son Megapenthes after Menelaus died.
http://en.wikipedia.org/wiki/Helen
