Fangorn Forest is the Middle-earth forest home of Treebeard in J.R.R. Tolkien’s The Lord of the Rings.
Fangorn lies at the southern end of the Misty Mountains, near Rohan and Isengard. It is an ancient woodland inhabited by Ents, shepherds of trees whose language and lives operate on a far slower timescale than those of humans or hobbits. Treebeard, also called Fangorn, is the oldest and most important Ent encountered by Merry and Pippin.
After escaping from the Orcs who captured them, Merry and Pippin enter Fangorn and meet Treebeard. Their account of Saruman’s destruction of trees helps persuade the Ents to hold an Entmoot, a council that ultimately leads to the Ents’ assault on Isengard. The forest thus becomes a major setting in the resistance against Saruman’s industrial expansion.
Fangorn is not Mirkwood, the great woodland east of the Misty Mountains, nor Lothlórien, the Elven land. Tolkien also describes the Old Forest near the Shire, but it is a separate place.