J.R.R. Tolkien used Tengwar for the inscription on the Doors of Durin. The elegant characters appear above the entrance to Moria in The Fellowship of the Ring.
The inscription begins with the words “The Doors of Durin, Lord of Moria,” and continues with an invitation to speak, enter, and become a friend. Although the visible letters are Tengwar, the inscription’s language is Sindarin, one of Tolkien’s Elvish languages.
This distinction explains a common mix-up: Tengwar is a script, not a language. Tolkien designed it as a writing system capable of representing different languages, including Quenya and Sindarin. Cirth is another writing system in Middle-earth, associated especially with Dwarves, but it is not the script used for the Doors of Durin inscription.