The main villain of the series, Dr. K used to work for RobixCorp, but lost his arm in a lab explosion and now as a rogue robot inventor who uses his smarts for evil. In Season 1 he's after a substance called Solex to build the ultimate robot and destroy Bubble Town. His main robot is Kolossal, but he has his own line of evil robots such as Katastrophe, Kannon, Krab, Klawber, the Kulminator and Kilobot.

(Source: Wikipedia)