Hithaeglir is a mountain range in the fictional world of Middle-earth, created by J.R.R. Tolkien. It is located in the northern part of Middle-earth and serves as a natural barrier between the regions of Eriador and Rhovanion. The mountains are known for their rugged terrain and harsh weather conditions. The range is significant in Tolkien's works, particularly in The Hobbit and The Lord of the Rings. It is home to various creatures and plays a crucial role in the journeys of characters like Bilbo Baggins and Frodo Baggins, who must navigate its challenges during their adventures.