Mr. Twit is an unkempt, cruel retired circus monkey trainer who spends his days being malicious to animals and playing terrible tricks on his wife. He firmly believes his messy facial hair makes him look wise, though his actions prove him to be deeply foolish. He catches birds by smearing strong glue on a dead tree in his yard, intending to bake them into weekly pies.

Mrs. Twit is the bitter wife of Mr. Twit. Though she was once lovely, years of vindictive thoughts have physically altered her appearance, which leaves her exceptionally ugly on the outside as well. She carries a walking stick that she uses primarily to hit things, particularly the captive monkeys in her yard. She continuously engages in a cycle of cruel practical jokes with her husband.

Muggle-Wump is the lead monkey of a family kept captive by the Twits. Brought over from Africa, he is forced to endure grueling training for an upside-down monkey circus under the threat of physical punishment. He is observant, hates his cruel captors, and looks for ways to protect the local birds from the deadly glue traps in the garden.

The Roly-Poly Bird is a colorful avian visitor from Africa who speaks multiple languages. Because he can understand both the African language of the monkeys and the English language of the local birds, he serves as a crucial communicator. He uses his translation abilities to help the local birds avoid the sticky traps set by the homeowners.

Fred is a local man who works as a gas meter reader for the town. He visits the Twits' property to perform his routine job, interacting with the bizarre environment the couple has created at their home.