Beau, or Bob, is an entity that feeds on fear who has long ago learned that a LOT of people are scared of clowns. They have had their current form since the fear of clowns has become widespread and relish in the effect it has on regular humans.

Instead of seeking out people to spook, however, Beau has found their place at the Yes You Can Carnival, a place run by the vampire Carnie that gives a home to supernatural creatures who would otherwise struggle to fit into human society and adapt to the new ways of hiding. Beau has an innate and almost artistic sense for fear, and runs the haunted house and other sideshows that are geared to giving you a spook. Beau themself is usually within the haunted house, having a good time with all the shrieks a scary clown in "heavy makeup" can cause.

Beau is essentially an evil creature and has a difficult time interacting with humans normally, and always carries a low-key frightening aura with them. Aware of this fact, they tend to stick to the carnival and not wander around where people might try to talk to them, but if necessary they have an enchanted nose-ring to dampen their unsettling aura and make them appear human. They enjoy the new, more wholesome lifestyle of the carnival and have come to love the unique flavour of fear for fun.

Beau can become invisible and has powers of illusion that can change their appearance and the environment around them. They constantly use this to mess with people, feeding off the unease and fear it creates, but the less attention they are paid the weaker their powers become and most of the other carnival workers are completely unphased at this point and just ignore it because heck, that's just Beau.

Instead of speaking, Beau prefers to gesture, mime, and make exaggerated expressions to communicate. This is often accompanied by faint illusory sounds like jingles and honks. They can talk perfectly fine, however. Beau's usual speaking voice is soft and high pitched, almost falsetto. That falsetto occasionally breaks and drops at weird moments into a grating baritone, creating an odd and offputting warble (similar to Dr. Hogback but in reverse).

Illusions

Beau's illusions are very powerful when at their full potential, affecting all senses with the intensity of an advanced hallucination. What they can't do is push, injure, or otherwise physically influence anything. Although Beau may "transform" into different shapes, their real physical body is always still there, often invisible, and it's the only way they could actually pick something up or open a door. The more belief and attention the illusions are given the stronger they are, so when Beau was still actively hunting people to inspire terror they would always start small: Ghostly chills and moving shadows, smears of blood on walls etc.

Other Boogeyman stuff

A creature of darkness, Beau can merge with shadows and sneak around which is very startling for someone of their size. They can inflict the damage one would expect from a large person with claws, sharp teeth, and a huge belly mouth, but are much more interested in just giving people a scare. The inside of their body is a small dimension of its own. Anyone unfortunate enough to be swallowed finds themselves in a blank dark room, at the mercy of Beau's fear tricks until they decide to let them out. These days Beau is reluctant to perform such extreme actions, however, mainly out of respect for not causing the carnival trouble.

Beau sustains injury and heals normally but doesn't seem particularly bothered by pain and doesn't have any "vital areas" like organs. Their greatest weakness is being ignored/not being able to cause fear, because their power is greatly lessened when people don't pay attention to them or aren't bothered by their appearance. Beau is unable to cross barriers of salt, and knowing Beau's true name (a secret lost to time) would grant the one who knew it complete power over them.