Dr. Zalost is a scientist suffering from depression who lives in his tower along with his henchman, and pet, Rat. He was seen in the season two final episode "The Tower of Dr. Zalost."
Dr. Zalost desires only one thing: to make everyone as miserable as he is. What caused him to be in his miserable state is unknown. Another characteristic known about him is his contempt for humanity believing them to be selfish. Ironically, he is a hypocrite because he according to him, if he is not happy then nobody deserves to be. His relationship with his pet Rat is seen as complicated and, most of the time, abusive. Although he views Rat as his only friend, he regularly berates him for not giving him proper hugs and for not attacking the Baggs. However, at the end of the episode, Rat and Dr. Zalost reconcile with one another.