Who is Thingol from The Silmarillion and what is their importance?

King Thingol is originally called Elwe and leads the host of Teleri from Cuiviene with his brother, Olwe. As he wanders about, he is enchanted by the Maia, Melian, and they are married. They have a daughter, Luthien. King Thingol rules Doriath and is called the Hidden King, Grey-cloak and Grey-mantle. He sends Beren on a quest to retrieve a Silmaril in order to earn Luthien's hand in marriage. After the Silmaril is retrieved, he has it set in the Nauglamir and is killed by the Dwarves for refusing to relinquish the Nauglamir.