Glóin was one of the thirteen companions of Thorin Oakenshield on the Quest of Erebor. A skilled fire-maker, he thought little of Bilbo Baggins at first, but gained a new respect for the hobbit by the quest's end. He has dwelt at the Lonely Mountain ever since. Glóin's brother Oín, who also accompanied Thorin on his great quest, journeyed into Moria with their kinsman Balin but was never heard from again.

After the rise of the Shadow in the East, Glóin and his son Gimli brought news to Rivendell of the Enemy's movements and sought the wisdom of Elrond Half-elven. Both attended the great Council of Elrond, where Gimli was chosen to become one of the nine members of the Fellowship of the Ring, whose task it is to bear the One Ring of Sauron to Mount Doom and cast it into the Chamber of Fire. Glóin, with his entourage, set about clearing the outcast Dourhands from the passes of the Misty Mountains, making safe the way from west to east.

Glóin is a character who appears in both The Hobbit and The Lord of the Rings. In The Lord of the Rings Online™: Shadows of Angmar™, he can be found encamped in the Misty Mountains, overseeing a defense against the Dourhands.