Maniac who origins are unknown, although Riviera tends to speak with a spanish accent. Badger faced off with the Badger when both were hired by rival appliance salesmen. Some time later, Badger caught Riviera working for IBOB to kill animals so the cult could use the blood to break down dimensional barriers, at which point Badger beat the doctor senseless.
 
Dr. Riviera showed up years later helping a terrorist named Pavlov to wire a horse with explosives in an attempt to kill the President during the Superbowl.