Kull is the hero Howard conceived before Conan, set in the remote Thurian Age before the sinking of Atlantis. Rising from barbaric origins, he seizes the throne of Valusia by force and confronts the deep corruption lurking within ancient civilisation.
His most celebrated story, "The Shadow Kingdom," pits him against the Serpent Men — shape-shifters who have infiltrated humanity at every level of power. This theme of hidden inhuman evil became a cornerstone of Howard's mythology and fed directly into the Hyborian Age cycle.