"The Door of Night" by John Howe
"The Door of Night" by John Howe
Originally done for the cover of The Book of Lost Tales 2, Grafton Books, 1992
More info on the subject matter https://lotr.fandom.com/wiki/Door_of_Night
But Morgoth himself the Valar thrust through the Door of Night beyond the Walls of the World, into the Timeless Void; and a guard is set forever on those walls, and Eärendil keeps watch upon the ramparts of the sky.