I mentioned Pauline Hickey earlier in this thread, and I'll stand by that, but add, after a bit of thought, Joan Brinkman and "Sydney Hearthstone" aka "Ruta Davis" aka "???".
Joan Brinkman had a combination of face and figure almost unmatched, with arguably the greatest *eyes* ever seen on a figure model. And while serious collectors avidly accumulate photos of her, she seems to go largely unrecognized today.
Sydney Hearthstone, on the other hand, truly *is* a "one hit wonder", appearing just a couple of times in Fling, under two different names, and then, seemingly, never again.