It's true that the story has plenty of dark and menacing creatures, but they are not traditionally understood as "devils" in the way you might find them in Christian mythology.
Here are some of the most common "evil" beings in Tolkien's world:
* Orcs: These are brutal, savage creatures that serve Sauron, though they were originally corrupted Elves.
* Trolls: These are monstrous creatures of immense size and strength.
* Nazgûl: These are wraiths or Ringwraiths, the servants of Sauron, each bound to a powerful ring.
* Sauron: The main antagonist of the story, the Dark Lord who seeks to dominate Middle-earth. He is a fallen Maia, a powerful spirit who once served the Valar (the angelic beings who created the world).
While these creatures are certainly evil, Tolkien's world has a more complex and nuanced view of good and evil than simply labeling them as "devils." They are all part of a larger cosmic story with its own set of rules and motivations.