Borin (T.A. 2450 – 2711, aged 261 years) was a dwarf of Durin's folk, the younger son of King Náin II. During his youth, his house lived in the dragon-plagued Grey Mountains where his brother and nephew were slain. Durin's folk then divided, with some journeying back to Lonely Mountain under King Thrór while others followed Grór to the Iron Hills. Borin followed Thrór to the Lonely Mountain and lived there till his death.