What fictional language appears in the inscription on J.R.R. Tolkien’s One Ring?

The inscription on J.R.R. Tolkien’s One Ring is written in the Black Speech.

Sauron created the Black Speech for the servants of Mordor, and the Ring’s inscription is the best-known surviving example. Its words are: “Ash nazg durbatulûk, ash nazg gimbatul, ash nazg thrakatulûk agh burzum-ishi krimpatul.” In English, the verse begins, “One Ring to rule them all.”

The inscription is written in Tengwar characters, but the script and the language are different things. This distinction causes a frequent mix-up: Tengwar is a writing system, while Black Speech is the language used for the Ring verse.

Black Speech is also different from Quenya and Sindarin, the major Elvish languages Tolkien developed. The Ring’s language reflects Sauron’s attempt to impose a single power over the peoples of Middle-earth.