Once a proud and noble Martian, he was turned to turned to clay by the jealous Queen Azura by means of the magic power she drew from the white sapphire, and banished to the undergrounds caverns of the Valley of Desolation. Over a period of time the Clay King saw the number of his fellow Clay People grow and although they were unable to leave the caves, he oversaw moves to increase their power so that, should the opportunity arise, they would be in a better position to reclaim Mars from Azura. Secret tunnels and transportation were established which extended all the way from their dwellings to the foundations of Azura's palace, and traps were set in their caves to allow them to capture trespassers.
Desperate to free his people, and suspicious as to their motives, the Clay King originally made prisoners of Flash Gordon and his friends and blackmailed Flash into helping his cause. Eventually the Clay King realized that Flash was sincere and a friendship was established. The Clay King then offered much assistance to Flash, such as the use of the Vacuum Car and also the use of the Healing Chamber to cure the injured "Happy" Hapgood.
The Clay King was subsequently restored back to his normal form when the white and black sapphires were both destroyed. With Queen Azura dead and Ming the Merciless removed, the Clay King was declared the next ruler of Mars.
The Clay King was portrayed by actor C. Montague Shaw.