This is a US award given annually in the years 1979 to 1985 for work in the field of fantasy.
It is named after the demon servants of Melkor the Dark Enemy, who are referred to mainly in the back-story to J.R.R. Tolkien's Lord of the Rings though one malign sleeper Balrog does survive long enough to be defeated by Gandalf.
Other awarded writers:
- Anne McCafffrey
- Katherine Kurtz
- Roger Zelazny
- C.J. Cherryh
- Stephen King
- and others
Taken from The Encyclopedia of Fantasy by John Clute and John Grant, Orbit 1997.