Styggron

Chief Scientist Styggron was the leader of the Kraals' Armoury Division. He created the Kraal androids and the replica of Devesham based on Guy Crayford's memories. He used them to study humanity for the invasion of Earth. He delayed the experiment when the Fourth Doctor and Sarah Jane Smith arrived, as he saw a chance to study a Time Lord.

After capturing them and making android duplicates, he travelled to Earth with Crayford and began the takeover of the Space Defence Station. When he learned the truth, he turned against Crayford and shot him dead, but was killed when exposed to the virus he had created to wipe out humanity. The Kraal invasion fleet, led by Marshal Chedaki, were presumably left waiting in vain for Styggron's invasion signal. (TV: The Android Invasion)

He was succeeded as Chief Scientist of all the Kraals by Tyngworg. (AUDIO: The Oseidon Adventure)