Borin was a Dwarf of Durin's Folk, the second son of King Náin II and brother of Dáin I.After his brother and younger nephew Frór were slain, Borin departed from the Grey Mountains with his younger nephew Thrór to the Lonely Mountain and lived there until his death. He was an ancestor of both Balin and Gimli of the Fellowship of the Ring. He died in TA 2711.