In J. R. R. Tolkien's fantasy writings, Isengard (/ˈaɪzənɡɑːrd/) is a large fortress in Nan Curunír, the Wizard's Vale, in the western part of Middle-earth. In the fantasy world, the name of the fortress is described as a translation of Angrenost, a word in Tolkien's elvish language, Sindarin, a compound of two Old English words: īsen and ġeard, meaning "enclosure of iron".
In The Lord of the Rings, Orthanc, the tower at the centre of Isengard, is the home of the Wizard Saruman. He had been ensnared by the Dark Lord Sauron through the tower's palantír, a far-seeing crystal ball able to communicate with others like it. Saruman had bred Orcs in Isengard, in imitation of Sauron's forces, to be ready for war with Rohan. The Orcs cut down many trees in the forest of the Ents, who retaliate by destroying Isengard while the army of Orcs is away attacking Rohan at Helm's Deep. However, the Ents are unable to harm the tower of Orthanc. Saruman, isolated in the tower, is visited by members of the Fellowship of the Ring; his staff is broken by the Wizard Gandalf.