In J. R. R. Tolkien's Middle-earth fiction, Man and Men denote humans, whether male or female, in contrast to Elves, Dwarves, Orcs, and other humanoid races. Men are described as the second or younger people, created after the Elves, and differing from them in being mortal. Along with Ents and Dwarves, these are the "free peoples" of Middle-earth, differing from the enslaved peoples such as Orcs.

Tolkien uses the Men of Middle-earth, interacting with immortal Elves, to explore a variety of themes in The Lord of the Rings, especially death and immortality. This appears throughout, but is the central theme of an appendix, "The Tale of Aragorn and Arwen". Where the Hobbits stand for simple, earthbound, comfort-loving people, Men are far more varied, from petty villains and slow-witted publicans to the gentle warrior Faramir and the genuinely heroic Aragorn; Tolkien had wanted to create a heroic romance suitable for the modern age. Scholars have identified real-world analogues for each of the varied races of Men, whether from medieval times or classical antiquity.

The weakness of Men, The Lord of the Rings asserts, is the desire for power; the One Ring promises enormous power, but is both evil and addictive. Tolkien uses Aragorn and the warrior Boromir, the two Men in the Fellowship that was created to destroy the Ring, to show opposite reactions to that temptation. It becomes clear that, except for Men, all the peoples of Middle-earth are dwindling and fading: the Elves are leaving, and the Ents are childless. By the Fourth Age, Middle-earth is peopled with Men, and indeed Tolkien intended it to represent the real world in the distant past.

Commentators have questioned Tolkien's attitude to race, given that good peoples are white and live in the West, while enemies may be dark and live in the East and South. However, others note that Tolkien was strongly anti-racist in real life.

The race of Men in J. R. R. Tolkien's fictional world, in his books The Hobbit, The Lord of the Rings and The Silmarillion, is the second race of beings, the "younger children", created by the One God, Ilúvatar. Because they awoke in the First Age at the start of the Years of the Sun, long after the Elves, the Elves called them the "afterborn", or in Quenya the Atani, the "Second People". Like Elves, Men first awoke in the East of Middle-earth, spreading all over the continent and developing a variety of cultures and ethnicities. Unlike Tolkien's Elves, Men are mortal; when they die, they depart to a world unknown even to the godlike Valar.

Men are one of the four "free peoples" in the list-poem spoken by the Ent Treebeard; the others being Elves, Dwarves, and Ents. Hobbits, not included on that list, were a branch of the lineage of Men. Hobbits were not known to the Ents, but on meeting Merry and Pippin, Treebeard at once worked that people into the list.

The concept of the free peoples is shared by Elrond. The Tolkien scholar Paul H. Kocher writes that, in the style of the medieval Great Chain of Being, this list places Men and the other speaking peoples higher than the beasts, birds, and reptiles which he lists next. "Man the mortal, master of horses" is listed last among the free peoples, who were created separately.

Although all Men in Tolkien's legendarium are related to one another, there are many different groups with different cultures. Those on the side of the hobbits in The Lord of the Rings are the Dúnedain, the men who fought on the side of the Elves in the First Age against Morgoth in Beleriand, from whom other friendly groups, the Rangers including Aragorn, and the men of Gondor are descended; and their allies the Rohirrim.