Darval was an Earthling criminal from planet Earth who was marooned on the asteroid Rogues’ Rock for murdering several fellow crewmembers on an intergalactic exploratory colonizing mission from his home planet. While stranded, Darval was deformed and twisted partially by radiation but mostly by his own evil rage towards Earth.
Eventually he was rescued by a ship from Zorian Engineering. He seized a ship carrying cyborgs known as Ormazoids for an experiment in genetics and used them in a plot to invade Earth, but he was foiled by “Ixionian” and the Doctor after they seized the Master Genetic Code Signifier. He slunk off to plot his revenge.