Thráin

Thráin II is the father of Thorin Oakenshield, and the son of Thrór. He became heir of the lost King under the Mountain and King of Durin's Folk as Thráin II when his father Thrór was killed at Moria, and he was a direct descendant of Durin the deathless.

Thráin fled with a small group of companions when the dragon Smaug descended on Erebor the Lonely Mountain, and took the kingdom. Together with the other survivors and his son Thráin fled to the Ered Luin, where there still were old dwarven mines. Thráin took with him a map which showed a secret entrance to Erebor.

However, as Thráin grew older he wanted to reclaim his kingdom. He left for Wilderland, but was captured by Sauron and trapped in Sauron's stronghold Dol Guldur in southern Mirkwood. Sauron took from him the last of the Dwarven Rings of Power, and left him in his dungeon to die.

While on a mission to Dol Guldur, Gandalf the Grey came upon Thráin, and was given the old map. Gandalf promised to deliver it to Thráin's son, but Thráin at the time had forgotten his name so Gandalf did not expect to be able to fulfill this promise. There Thráin died.

Much later Gandalf met with Thorin near Bree, and realized who the Dwarf he had met in Dol Guldur had been. He promised to help Thorin in his quest to the Lonely Mountain in many ways, the most notable of which was by inviting a hobbit named Bilbo Baggins along to fulfill the role of thief.