People of the Monolith
From Lin Carter, Lovecraft: A Look Behind the Mythos: "...in 'The Black Stone' [Robert E.] Howard invents a "mad poet" of his own, a sort of English-speaking version of Abdul Alhazred named Justin Geoffrey, author of a nightmarish poem entitled "The People of the Monolith." A versifier of considerable gifts, Howard gives us a morsel of Geoffrey's talent by quoting a few lines of his as the heading of this story:
They say foul beings of Old Times still lurk In dark forgotten corners of the world, And Gates still gape to loose, on certain nights, Shape pent in Hell.
Another story, 'The Thing on the Roof,' picks up and elaborates on both Justin Geoffrey and Von Junzt, and introduces Xuthltan, who plays a major part in yet another tale, 'The Fire of Asshurbanipal,' not to be published for some years."
("The Thing on the Doorstep")
See also: Justin Geoffrey