Graylorne
Archmage
Hambly - Quite a few titles, once widely read, most apparently falling into obscurity. "Walls of Air', 'Ladies of Mandrigyn', 'Knight of the Demon Queen', and quite a few others. Magicians generally activiely persecuted, genuinely evil demons, and characters ranging from good to coldly treacherous. Never seen her works mentioned here, despite their one time popularity.
I remember Hambly, I had Mandragyn and the Walls of Air books. I also remember her as pretty dull. I know Simak, but not the title you mention. I have at least 2 of Norton's Witchworld books. Always was a fan of her, but I don't really remember those two. Most of the rest I haven't even heard of. That's my problem with many American titles even now. Either they never crossed the Atlantic or they were promoted so marginally that no-one over here ever heard of them.