Primordial

Progenitors (also known as Primordials) are demons of extraordinary power. According to Leon Cromwell, each of them is referred to by their signature colors, in place of an actual name.

However, each one appears to have a name, or something similar:

The Red Progenitor, Rouge (Guy Crimson)

The White Progenitor, Blanc (Princess Blanche Nam Silberia)

The Black Progenitor, Noir (Diablo)

These are the only three known thus far, but there are seven in total.

Appearance
Black : Wears a full butler attire with white gloves. He has black hair with a strand of red in the front

White Has silver hair, snow white skin, and red eyes. She is very beautiful.

Red Has crimson red hair and is very beautiful.

Personality
According to Leon Cromwell, they are heretical and often troublesome.

Chronology
The term first appeared in Black and a Mask, although the term Primordials was used in the side novel story The Lake Shore Dyed Scarlet Incident.

Black was summoned by a woman, who begged him to do something to 'them'

"If you grant my wish, I don't care if you're a demon! You can have my soul! So, please... Make them... Make them..."

Black agreed to her wish, and in exchange, devoured her emotions.

Black then hunted down an Archdemon, supposedly fulfilling his contract.

Abilities
Much is unknown about the prowess of the Progenitors, but it can be inferred they are mighty individuals, as Black states that even a Superior Spirit is a hassle, but no real problem

Black's Abilities:

 Fire: The ability to summon fire

Claws: Black can produce very long, sharp claws on either hand

Speed:  Black is extremely fast, even to the point where it seems he is teleporting

Trivia
Diablo is the Black Progenitor

Guy Crimson is the Red Progenitor

Princess Blanche Nam Silberia is the White Progenitor