Evil beings (possibly lesser Valar) and servants of Morgoth, at least one of whom survived Morgoth's defeat in the First Age. The surviving Balrog hid in the deeps of Kazad-dum until Third Age 1980, when he was released by the Dwarves. Known as Durin's Bane, he was the sole cause of the Dwarves' flight from Kazad-dum. The Balrog was slain by Gandalf when the Companions of the Ring passed through Moria.

Black crows, possibly from Fangorn and/or Dunland, used as spies by Saruman.

Originally Men, the Nazgul were each given one of the Nine Rings by Sauron in the Second Age, becoming his chief servants when the Rings enslaved them. They acted as Sauron's messengers and scouts and led his armies. Their powers were strongest at night, but they feared fire and the name of Elbereth. They could only be wounded by weapons with special spells upon them, and any blade which touched them melted. As Black Riders, they followed Frodo from the Shire on his flight to Rivendell. The Lord of the Nazgul, their chief, wounded Frodo, but he escaped them. When their steeds (swift black horses) were destroyed in the river that borders Rivendell, they reappeared in the skies, riding flying beasts. The Lord of the Nazgul was wounded by Eowyn in the Battle of the Pelennor Fields. Because their powers were directly linked to Sauron's, his destruction at the end of the Third Age resulted in their own. Other names for the Nazgul include the Nine Riders and the Ringwraiths.

The Hobbits' name for Orcs.

Strain of Orcs bred by Sauron in Mordor during the Third Age. Used as soldiers by both Sauron and Saruman, the Uruk-hai were almost as tall as Men. They were black and slanty-eyed with straight, strong legs, and they considered themselves superior to other Orc breeds.

Numenorean servant of Sauron who became a great sorceror and was therefore able to extend his life by thousands of years. By the War of the Ring, he had become the Lieutenant of the Tower of Barad-Dur and could no longer remember his real name. He was doubtless killed when Sauron fell.

A Great Spider whose offspring dwelt in Mirkwood. Shelob's lair was a vast den under Cirith Ungol, one of the entrances into Mordor. At around Third Age 3000, she captured Gollum who then led Frodo and Sam into her clutches during their journey to Mount Doom. Shelob was blinded and wounded by Sam, who used the phial of Galadriel and Sting against her, and she may eventually have died of her wounds or of starvation due to her inability to hunt blind.

The greatest dragon of his time, Smaug drove the Dwarves away from the Kingdom under the Mountain in 2770. He remained there for nearly two hundred years, until 2941, when he was disturbed by Thorin and Company. After unsuccessfully trying to find and kill the company of Dwarves, he attacked nearby Esgaroth where he was slain by Bard the Bowman.

Evil race of Middle-Earth, originally bred by Morgoth in mockery and imitation of Ents. Trolls were very large, strong, ugly, and stupid. They hoarded treasure and killed for pleasure, but they would turn permanently into stone when exposed to sunlight. There were at least four strains of trolls: the Stone-trolls, Cave-trolls, Hill-trolls, and the Olog-hai, which were created by Sauron during the Third Age. The trolls encountered by Thorin and Company were Stone-trolls. Trolls probably became extinct in the Fourth Age.

Evil wolves of Rhovanion, allies of the Orcs and servants of Sauron.

A many-tentacled creature who guarded the West-gate of Moria for a period of time during the Third Age, the Watcher lived next to the gates in a lake it created by damming a nearby stream. It was perhaps related to the nameless things below Khazad-dum, but while it was definitely evil, it is unclear whether it was controlled by Sauron or the Balrog.