The Silver Surfer design was actually all Kirby! The lore is that Stan received the FF pages in from Jack to dialogue, and there was this random bald dude on a surf board that they’d never discussed and Stan hadn’t put in the “Marvel style” plot.
Stan of course took it & ran with it. I seem to recall Stan’s philosophical take might not have been quite what Kirby was envisioning and was actually a source of tension, which of course led Buscema to be the artist on that first classic solo series.