Luthien, daughter of Thingol, king of Doriath, was born in the Ages of Starlight. The name 'Tinuviel,' as is often her title, comes from the name given her by Beren, son of Barahir, her human lover, and means 'Nightingale' in Sindarin. Luthien is considered the most beautiful maiden of any race ever born. She is the daughter of an elf, Thingol, and the Maia spirit Melian, queen of Doriath. Her life in involved mostly in story with the human Edain Beren, whom she fell in love with against her father's will. However, because she had made Thingol swear not to harm Beren, he instead set upon him the Quest of the Silmaril. Beren and Luthien, after many hardships including imprisonment on Sauron's (somethimes called 'Thu') Isle, reach Angband and recover a Silmaril from the Iron crown of Morgoth, the enemy. Beren loses it when the hand holding the stone is bitten off by the werewolve Carcharas, but recovered when the wolf is killed in Doriath. Luthien dies in grief when Beren dies (at the time of the Silmaril's recovery from Carcharoth's belly) but, after singing a song of sadness before Mandos (q.v.), she and Beren are granted new mortal lives together. During this life Luthien gives birth to Dior, future king of Doriath and father of Elured, Elurin, and Elwing.
The Tolkien Encyclopedia
The Encyclopedia of Middle-earth
Hypertextual System by FMI Publishing, 1995