Margaret is the overbearing rich boss of Flying John. All she truly cares about is her dog Foo-Foo, and she never allows John to have any fun. Foo-Foo doesn't like John, as she's shown growling at him whenever Killjoy Margaret scolds him.
Margaret and her dog Foo-Foo are one of the last people seen leaving a hotel alongside Flying John. As John tries to play hopscotch, Margaret scolds him to keep going just as the camera cuts to the subway area. Margaret later appears during the part where she and John stop buy a peanut stand where John interacts with a nearby monkey just as Margaret tells him to hurry up much to her chagrin. She and John later stop by at the "Le Pampered Pooche" per store for her dog with multiple items, causing John to look at the total amount of items collected for her dog. Towards the end of the segment, she and John walk by a nearby construction site while Joe receives a job routine as a construction worker just as a pipe pushes the hook causing Margaret and her dog to be stuck in the construction site. Upon noticing this, John finally decides to have fun after being free from Margaret's harshness just as Margaret angrily tells Joe to get her out of the construction site in anger and defeat.
- Killjoy Margaret is very similar to the Wardrobe, both in appearance and personality.