If they were comic books, the illustrator was Frank Frazetta.
If they were print novels, the illustrator was Boris Vallejo.
But the Peruvian-born Vallejo was more naturalistic in his drawings, he used a brighter color palette, lots of gold skies and gleaming muscles, and his work was more erotic -- these barbarian heroes had obvious bulges. .
His wife, Julie Bell, is also a former bodybuilder and illustrator, who has a similar style, except her women aren't clinging to the legs of muscle gods: they're female bodybuilders and barbarian heroes in their own right. She has illustrated over 100 covers for science fiction novels since the 1990s.