Our time at TSR didn't overlap,* but he's one of the artists whose work I was familiar with as a gamer for its appearance in so many of the early D&D/AD&D modules, like Tom Moldvay's X2. CASTLE AMBER. A legendary figure, one of the Giants in the Earth, as it were, he came into his own after he left TSR and became the artist for PARANOIA, a perfect matching of artist and game.
I did get the chance to work with him once, when I edited Jeff Grubb's MARK OF AMBER boxed set (1995), and asked the art director if we cd use Holloway as our freelance artist. The result skewed sillier that I'd hoped but I was still glad to have had the chance to work with him on a project.
Oddly enough I'd been thinking about him last night when I dug out my old copy of CHATEAU d'AMBERVILLE to review its Clark Ashton Smith content; looking it over has got me thinking of running it as a solo game on weeks when my unusual gaming groups can't get together.
--current reading THE AVEROIGNE CHRONICLES
* he'd been there the early eighties whereas I didn't sign on until a decade later