In the Dark Sun setting from AD&D, the offspring of humans and dwarves are also infertile. Also called muls, which isn't the most creative move but hey. I don'

In the Dark Sun setting from AD&D, the offspring of humans and dwarves are also infertile. Also called muls, which isn't the most creative move but hey. I don't recall there being any children of dwarves and men in the Tolkien legendarium, though I've not read it all by any means. Given how common "interfertile but with sterile offspring" is between related species in nature, it's relatively rare in games and fantasy settings.