Dark Clowns

The Dark Clown is the physical representation of madness. They can only take form after a sufficiently large quantity of this particular force of chaos has collected at a singular location. Usually this process occurs only in the wake of a Kishin (Demon God), whose corrupted soul emits a wave of madness so substantial that it can affect the entirety of the world upon release. However, it is only when this insanity gathers at a susceptible destination can a clown be brought into reality, by using the immediate area as a "cradle" from which to emerge.

Description
Upon its "birth", a clown's solitary purpose is the continued dispersal of the condition that created it, with the creature serving almost like a "contagion of madness" acting just to ensure that this particular infection continues its advancement along its destructive path. In order to achieve this aim each and every clown possesses a wavelength of madness that is capable of drawing other individuals in the immediate vicinity into the clutches of its insanity, by inspiring terrible visions within the minds' of its victims. However, how effective this actually is, is entirely dependent upon each individual clown's strength and how susceptible the afflicted person is.

Despite the uniformity in each individual clown's purpose and ability, their actual appearance varies greatly between them, with the only visible exception being that they all possess a vaguely humanoid structure in their stature. The remainder of their bodies are seemingly composed from a random assortment of items, which is as distinctive as each particular clown.

Along with their own distinct powers and characteristics, they are all capable of regeneration and reanimation shortly after death by feeding on Asura's Madness wavelength. Without it, this power is nullified.

Man-Made Clown
As the name suggests, a Man-made Clown is one of artificial construction, created from another source of madness than what is normally considered natural, such as the Black Blood devised by Medusa Gorgon. Even though the substance from which they are generated is different, these man-made clowns possess all of the defining traits and capabilities of other clowns but due to the presence of impurities within the madness they originated from, they are typically considered inferior or even perverse in comparison to their natural brethren.

Clowns

 * The Clown: Being the first of these entities to make an appearance, this clown holds the unusual title of simply the Clown. It confronted and was later defeated by Maka Albarn, however, by narrowly managing to survive, it was able to reform itself and eventually draw even the Death scythe Justin Law towards Asura's bidding. As of Chapter 85 The Clown has been seen in a new appearance with Justin in the city of Ukraine. This one appears to have the power to speak and was likely assigned to him by the Kishin himself.
 * Kaguya
 * Moonlight
 * White Rabbit

Man-Made Clowns

 * The Black Clown: Black Clown is a man-made clown, born of Medusa Gorgon's experiments into the madness inducing Black Blood, in the hopes that it will bring Crona-her child, closer to her ultimate goal of creating a kishin.
 * The Purple-Dyed Clown: The Purple-Dyed Clown is a simple entity born of Medusa's experiments and resulting as a by-product of her research into the creation of the superior Black Clown.
 * The Clowns: The Clowns are the guardians of the last Demon Tool. The clowns are different from the one of the manga, even though their appearences are similiar. They are not the contagion of madness, but rather are two guardian machines, created by Eibon — and possibly Shinigami, that protect the last demon tool which is needed to activate Brew.

Trivia

 * The concept of the Clown was likely derived from the common phobia referred to as Coulrophobia, which is characterized by an abnormal or exaggerated fear of clowns.