Wikipedia
In the published version of The Silmarillion, Orodreth was an Elf of the First Age, the second son of Finarfin (with Finrod Felagund, Angrod, Aegnor, and Galadriel being his siblings), and a ruler of Nargothrond.
His name in Quenya was Artaresto and he was born in Valinor .
Orodreth held the tower of Minas Tirith on the island of Tol Sirion in the vale of Sirion until Sauron overran the isle and renamed it Tol-in-Gaurhoth. Orodreth then fled south to Nargothrond. Without the aid of Celegorm and Curufin, who had suddenly attacked the forces of Sauron with whatever forces they could gather, Orodreth might have fallen.
When Beren came to Nargothrond, Finrod went with him on his quest for the Silmaril. However Celegorm and Curufin the Sons of Fëanor were also at Nargothrond, and forced Finrod to lay down his crown. Orodreth took it, ruling as regent, but the Sons of Fëanor held the real power.
When news came that Finrod had been killed, the Sons of Fëanor were expelled from Nargothrond, and Orodreth became its leader.
When Túrin Turambar arrived in Nargothrond he gradually became its de facto leader, although Orodreth remained lord in name.
Orodreth had one daughter: Finduilas. He later died fighting the hosts of Morgoth and Glaurung the Dragon in the Battle of Tumhalad and Finduilas was taken and slain shortly afterwards. The only other member of the house of Finarfin to have descendants was Orodreth's auntie Galadriel, who had left Beleriand before the end of the First Age.