Ents are sentient beings in J. R. R. Tolkien's fantasy world of Middle-earth who closely resemble trees; their leader is Treebeard of Fangorn forest.

Tolkien stated that he was disappointed by Shakespeare's handling of the coming of "Great Birnam Wood to High Dunsinane hill"; he wanted a setting in which the trees would actually go to war.

Inspired by Tolkien and similar traditions, animated or anthropomorphic tree creatures appear in a variety of media and works of fantasy.

[T 2] Ents vary widely in personal traits (height, heft, colouring, even the number of toes), having come to resemble somewhat the specific types of trees that they shepherded.

[T 2] They destroy Isengard, tearing down the wall around it:[T 3] "If the Great Sea had risen in wrath and fallen on the hills with storm, it could have worked no greater ruin".

[T 12] Tolkien noted in a letter that he had created Ents in response to his "bitter disappointment and disgust from schooldays with the shabby use made in Shakespeare's Macbeth of the coming of 'Great Birnam Wood to high Dunsinane hill': I longed to devise a setting in which the trees might really march to war".

[T 13] The Ents ensured victory at the Battle of Helm's Deep by herding a forest of angry, tree-like Huorns there, to destroy Saruman's army of Orcs.

"(Mark 8:24) Algernon Blackwood's 1912 story "The Man Whom the Trees Loved" suggests that "trees had once been moving things, animal organisms of some sort, that had stood so long feeding, sleeping, dreaming, or something, in the same place, that they had lost the power to get away", which Groom remarks sounds just like Treebeard's account of Ents going "sleepy and 'tree-ish'".

[3] Commentators have observed that having the Ents march to war against the tree-destroyers represented a wish-fulfilment on Tolkien's part, concerned as he was with the increasing damage to the English countryside in the 20th century.

When Summer lies upon the world, and in a noon of gold Beneath the roof of sleeping leaves the dreams of trees unfold, When woodland halls are green and cool, and wind is in the West, Come back to me!

When Summer warms the hanging fruit and burns the berry brown; When straw is gold, and ear is white, and harvest comes to town; When honey spills, and apple swells, though wind be in the West, I'll linger here beneath the Sun, because my land is best!

Olsen sees in Tolkien's song of the Ents and the Entwives, supposedly written by Elves, "compelling insights on the complexities and conflicts of life in a fallen world.

He gives as examples the "apathetic isolationism" of Skinbark, who refuses to come out of his hills, and Leaflock's "somnolent oblivion", just standing in the long grass all summer doing nothing.

[15] Two of the Ents that appear in the season two episode "Eldest" are Snaggleroot and Winterbloom (voiced by Jim Broadbent and Olivia Williams[16]).

Ents appeared in the earliest edition of the roleplaying game Dungeons & Dragons in the 1974 white box set, where they were described as tree-like creatures able to command trees, and lawful in nature.

[17] In 1975, Elan Merchandising, which owned the game licence to the Tolkien estate, issued a cease-and-desist order regarding the use of the word "ent", so the Dungeons & Dragons creatures were renamed "treants".

[18][19] Heroes of Might and Magic V includes Treants as a part of the Elven alliance; however, due to copyright infringement issues, their look was changed[20] between the beta phase and the retail version, making them quadrupedal.