Circus Baby commonly referred to as Baby is the animatronic mascot of Circus Baby's Pizza World invented by Afton Robotics, LLC and made for Fazbear Entertainment, Inc. Baby is haunted by the soul of Elizabeth Afton, who was the daughter of the serial killer William Afton. However, during the completion ending, Elizabeth's soul was presumably set free. As Circus Baby, she is a very large female animatronic with an overall appearance reminiscent of a clown. She has auburn hair in high pigtails on either side of her head, held in place by blue hair elastics. She has bright green eyes, long, blue eyelashes, and short, blue eyebrows. The sides of her eyes are also covered in blue. Her mouth is opened in a wide smile, revealing small, flat endoskeleton teeth, framed by thin, red lips. Her cheeks are large, round, and red, and her squarish nose is red and slightly upturned and pointed. Her midsection is exposed, revealing a metal fan surrounded by an orange triangle with rounded points. Her limbs have silver segments in rectangular shapes, and her hands have red palms. The tips of her fingers, which appear to be ball-jointed, are not sealed, revealing shiny silver underneath, similar to the springlock suits. Her knees have round, shiny, silver caps, and parts of her limbs have what appear to be blue pins sticking out of them. She wears a red crop top with frills on the shoulders, and a matching, frilly, red skirt (which was changed in design for Special Delivery). The toes of her matching red shoes are pointed and curled, white on the bottom, and topped off with shiny, gold orbs (possibly bells); these are the shoes worn by a jester. Under her skirt, she wears red and orange striped panties; this can only be seen through the error of one of her images in the game files. She holds an orange microphone with red accents in her left hand. Circus Baby is a tragic, sophisticated yet sinister animatronic.

Circus Baby:sitting down watching the cameras