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, and used them to study humanity in preparation for the Kraal invasion of Earth. He delayed the conclusion of the experiment when the Fourth Doctor and Sarah Jane Smith arrived, as he saw an opportunity to study a Time Lord. After capturing them and making android duplicates of them, he traveled to Earth with Crayford and began the takeover of the Space Defence Station. He shot and killed Crayford when he learned the truth and turned against him, but was killed when he was exposed to the virus he created to wipe out the humans. (DW: The Android Invasion)