The fictional language spoken by Sauron’s servants in J.R.R. Tolkien’s writings is the Black Speech.
Tolkien created the Black Speech for Sauron and his servants in Mordor. The best-known example is the inscription on the One Ring, beginning “Ash nazg durbatulûk,” which appears in The Lord of the Rings. The inscription expresses Sauron’s attempt to dominate the other Rings of Power.
The Black Speech should not be confused with Quenya or Sindarin, Tolkien’s most extensively developed Elvish languages. It is also distinct from Westron, the common language used by many peoples in The Lord of the Rings.
Tolkien supplied relatively little Black Speech compared with his Elvish languages. Its harsh sound and limited surviving vocabulary help distinguish it from the more elaborate linguistic traditions associated with the Elves.