DogDay is a toy produced by Playtime Co. debuting as a minor antagonist in Chapter 3: Deep Sleep. DogDay is the proclaimed leader of the Smiling Critters, which later stood after being transferred as an experiment for the Bigger Bodies Initiative.

DogDay originally coexisted in harmony with the Smiling Critters group, each having their own corresponding Bigger Bodies experiment. Following the events that took place during The Hour of Joy, the gang began to drift apart, leaving DogDay as the sole survivor. CatNap then imprisoned DogDay in a concealed cell within the Playhouse, subjecting him to endless torment due to his disobedience to The Prototype.