Platypus monster

A platypus monster was a platypus-based monster that was created by Dr. Phineastein and his assistant Ferbgor during the Victorian age. He has a rivalry with Jekyll Doofenshmirtz and ate him. This is an allusion to Perry and Heinz Doofenshmirtz's daily rivalry. During his journey through town, he passed a man in his underwear who had just announced he was over his fear that a giant platypus would see him dressed like that.

As a man-made creation, he cannot be considered an ancestor of Perry. ("The Monster of Phineas-n-Ferbenstein") He also appeared for a very brief moment in Rollercoaster: The Musical!