Male. An entity with a deep yellow, leathery smooth skin that carries a red balloon. They are characterized by running around excitedly, with red eyes and a red mouth fixed in a constant smile. They have teeth at their fingertips; if caught, they inject a toxin that causes immense pain and transforms the victim into another Partygoer. This Partygoer is always energetic and ends every sentence with "=)". To escape, one must hide under a desk or survive for 30 seconds, as they can only run for that long.

Male. An entity wearing a black hoodie, whose status as human or entity is unclear. He wears a blue mask with a "=(" expression. He used to help survivors trapped in the Backrooms and fought against the Partygoers after leaving them, but after many Partypoopers were killed due to betrayal by survivors, he is the last one remaining, having escaped via an elevator. He still helps survivors but flees from Partygoers due to past trauma.

A male, blue-colored Partygoer. He is roughly the same size as a standard Partygoer and has teeth at his fingertips like the others.

A male, red-colored Partygoer. He is stronger and more active than the standard ones, with even sharper teeth.

A male who is shorter than the standard Partygoer. He is green and even more energetic. The teeth on his fingertips are slightly blunt, leading to speculation that he might be a young individual.

A female who is larger than the Green Partygoer but slightly shorter than the standard ones. She is active, though not as much as the Green one. She has a girlish personality and very sharp teeth.