Durin I - Dwarf king of
Khazad-dum. Durin I was the first and eldest of the Seven Fathers of
the Dwarves who were conceived by Aule the Smith in the Ages of
Darkness. King Durin I's realm
was Khazad-Dum, the greatest Dwarf kingdom, which was found beneath the
Durin lived to such a great age that he was called Durin the Deathless. The name was also a reference to the belief that he would be reincarnated seven times as king of his people, and each time he would take the name of Durin.
After the destruction of Beleriand at the end of the First Age of the Sun, the histories of Elves and Men primarily tell us of the Dwarves of Durin's line.
References: Lord of the Rings, Silmarillion