Thangorodrim

Thangorodrim was an ancient mountain chain of three volcanic mountains, considered part of the Iron Mountains. The peaks were the highest in Middle-earth, and the fortress of Angband lay beneath them. Morgoth dwelled there in the First Age, and for a time they were also the aerie of the Great Eagles, until they relocated to near Gondolin.

The Balrog Thaurlach was also once a dweller of the Thangorodrim.

The Thangorodrim were utterly destroyed in the War of Wrath, and together with the rest of Beleriand, sank beneath the sea.