King of Doriath was the title of the rulers of the fair Elven Kingdom of Doriath during only the First Age.
History
The title originally belonged to Elu Thingol or Elwë. He held it for thousands of years from the time just before the Falmari reached Aman up in until the late First Age, when Thingol was murdered by the dwarves in the caves of Menegroth.
The only other holder of the title was Dior Eluchîl, son of Beren and Lúthien who was Thingol's only legal heir. Sadly, Dior held the title for only a few short years as he and his wife had become a victim of the Sons of Fëanor seeking the Silmaril, who had attacked Doriath and slew them both, ending the kingdom and the title.[1]
