Carter is known for his Jandar of Callisto book series that was an homage to Edgar Rice Burroughs' John Carter of Mars, and his sword and sorcery Thongor the Barbarian series. With L. Sprague de Camp, he compiled several books of Robert E. Howard's Conan tales; finishing and extending many of them, and also writing pastiche novels and short stories.
Carter was also a fantasy anthologist of note (the Flashing Swords series), and, as an editor for Ballantine Books, brought several obscure yet important books of fantasy back into print, including works by Lord Dunsany, James Branch Cabell, William Morris, and Evangeline Walton. He smoked and drank heavily and, consequently, died of throat cancer in 1988.
Novel: Jandar of Callisto, 1972
Anthology: Flashing Swords #1, 1973