A name among the Hobbits of the Shire for huge creatures - apparently Giants of some kind - seen passing through the Northfarthing in the later years of the Third Age. Many of the Hobbits themselves took them to be fanciful, though some (such as Samwise Gamgee's cousin Halfast) claimed to have witnessed the Tree-men for themselves. Tree-men took their name from the fact that they were as tall as trees, not necessarily that they looked like them (their actual appearance is never described, except they were said to have a stride of seven yards).

From their association with trees, and their extraordinary strides, it's natural to assume a connection of some sort between the Tree-men and the Ents. However, when Tolkien wrote his description of the Tree-men, the invention of the Ents still lay in the future, so the connection seems tenuous. It may be that the Tree-men of the Northfarthing represent the beginnings of his ideas about the Ents, which emerged more fully when he later created Treebeard and his people.