The Box Demon was hiding and living in Horst's inter dimensional money box. It appears as two long, black arms and hands with a green glow that stretch out of the box. The rest of its body is never seen outside of the box.
The demon appears after Eustace opens the box despite Shirley, Courage and Horst telling him not to. Once outside of the box, the demon grabs Muriel and Eustace as Courage runs to find Shirley (who was told to leave by Eustace after the box was opened). When Shirley returns to the farmhouse she walks up to the box before kicking it closed, causing the demon to drop Muriel and Eustace before retreating back into the box. As Shirley gathers the $100 that falls from the box, Eustace says he knew there was money inside of it. Eustace reopens the box before getting pulled inside of it as the box slams shut.
Personality
The demon box was known to be an aggressive and hostel demon that drags and imprisons alive anyone who chooses to be greedy for money. However, the demon reveals to have a sense of honor. It’s willing to give $100 to whoever proves themselves selfless. Shirley accused Eustace for disobeying Horst's wishes to get rid of the box. After she seals the box to save Muriel, Shirley hopes Eustace has learned his lesson. The demon rewards her with $100 for proving herself to be selfless.
Gallery
Trivia
The Box demon's arms and hands are the only parts visible. It is unknown what the rest of the body of the creature looks like as it was never fully emerged from the box.
Its possible the Box demon's purpose was to reward good hearted individuals whoever proves themselves selfless and honest by remaining unaware while they are doing good deeds which the box can sense their ongoing status.
