KoopaFanatic

Robert Silverberg. He did a couple of "collaborations" with Asimov, right before the latter died. Said collaborations were, as far as I could tell, largely Silverberg expanding the short story to novel length - I seem to remember Asimov had very little actual input beyond the outline stage.

But Nightfall is still a good read in both its forms. For some reason I especially like the names of the suns in the novel: Onos, Dovim, Trey, Patru, Tano and Sitha.