A powerful necromancer, Thulsa Doom is primary foe of Kull's comics version. He was often a featured foe in the Marvel Kull comics (for instance, "Kull the Conqueror" #3 and #7). Thulsa Doom returns in "Kull the Conqueror" #11, "By This Axe I Rule", based on an original story by Robert E. Howard. Posing as the nobleman Ardyon, he forms an alliance with four rebels within Valusia: the dwarfish Ducalon, the soldier Enaros, Baron Kanuub, and the minstrel Ridondo, who actually dethroned the hero, and set him on a quest to regain his lost kingdom, in the pages of his own comic, until it was cancelled. Kull resumes his quest in the pages of "Kull and the Barbarians", a black-and-white Marvel magazine format (published under the Curtis Magazines imprint). Thulsa Doom sent members of his Black Legion to ambush Kull and Brule, though they won the fight. Thulsa observed the battle through a magic crystal. Kull and Brule's ship was later attacked by a sea serpent, with which Thulsa may or may not have had anything to do.