Which fictional people did J.R.R. Tolkien call the Ents in Middle-earth?

J.R.R. Tolkien called the Ents the tree shepherds of Middle-earth.

Ents are ancient, intelligent beings who protect and care for trees. Their name comes from an Old English word meaning giant, and Tolkien’s Ents are especially prominent in The Lord of the Rings through Treebeard, their oldest and most famous leader.

The Ents’ storyline includes the Entmoot, a council held to decide whether they should act against Saruman. Their march on Isengard is a major turning point. Ents are sometimes confused with ordinary talking trees, but Tolkien distinguishes them as a people with their own language, history, and concerns.