|“||Where are you, Bozo? You need punishment. You can't hide forever, Bozo!||”|
— Unknown Shadow, "Welcome Back"
The Unknown Shadow is a mysterious creature (possibly object) with a somewhat ominous voice who was chasing "Bozo".
When Golf Ball's flashback occurred while she was in the Science Museum, you can see Bozo running nervously, then hides behind a vase. A large club with sharp spikes sticking out of it starts to hit the vase, slowly breaking it, with the voice telling the ball, which the voice referred to as "Bozo", to come out of hiding. Many think that this "Bozo" is Golf Ball, though it isn't confirmed, or is just simply the creature has mistaken her for someone else.
The Unknown Shadow has a voice similar to Orange Cary, a character in carykh's videos.
The Unknown Shadow may not be an object, because when scanned in a thermogram it is black and purple, meaning it is not hot. This may indicate that the shadow is not alive.