Primordial

Primordial Daemons (原初の悪魔) or Primordials (原初) also known as Seven Pillars of Primordial (原初の七柱), are the oldest and most extraordinarily powerful Daemons. According to Leon Cromwell, each of them is referred to by their signature colors rather than an actual name.

These "substitute names" don't count as their actual names in the true sense of being a named monster:
 * (Ultima)
 * (Testarossa)
 * (Carrera)
 * (Diablo)
 * (Misery)
 * (Rain)
 * (Guy Crimson)

Background
The Primordial Daemons trace their existence back to the dawn of time, when Veldanava, the creator god, brought forth the Seven Angels of Origin from the Great Holy Spirit of Light. As a result of this divine act, a profound cause and effect unfolded, giving birth to their demonic counterparts, the Primordial Daemons, who emerged from the Great Holy Spirit of Darkness as Devil Lords. With Rouge, the first and mightiest Primordial, as their overlord, they ascended to rule the Daemon realm, commanding unparalleled power and influence.

Rouge's might was so formidable that it prompted a challenge from the Blue and Green Primordial Daemons. However, both were defeated and subsequently resurrected under Rouge's control, becoming obedient to him. This left the remaining Primordial Daemons in a stalemate. However, Noir, the Black Primordial, engaged Rouge in a battle, resulting in a draw that earned Rouge's respect and acknowledgment.

Later on, Rouge, along with the summoned Blue and Green Primordials, was brought to the Central World, creating a power vacuum in their absence. Noir, the Black Primordial, pursued his own interests, while the White, Yellow, and Purple Primordials reached an agreement never to engage in direct combat. Instead, they engage in intricate games and employ cunning strategies to outsmart each other, preventing boredom.

At present, all the Primordial Daemons have incarnated in the Central World, setting the stage for their interactions and potential conflicts in this new realm.

Red Primordial, Rouge
Rouge, now known as Guy Crimson, is the first and most powerful among the Primordial Daemons. He proudly declares himself the first Demon Lord and possesses an overbearing personality. Guy is highly confident and doesn't hesitate to use coercion and threats to enforce his beliefs. He is recognizable by his flowing crimson red hair and eyes. Guy Crimson is loyal only to himself and currently resides in the Ice Continent as its ruler.

Black Primordial, Noir
Noir, now known as Diablo, is the Black Primordial. He is often considered an oddball among daemons due to his different values, particularly regarding the pursuit of power. After being summoned by Rimuru Tempest, Noir immediately pledged his undying loyalty and remains fiercely devoted to him. He is distinguished by his signature full butler attire with white gloves, as well as black hair with a strand of red in the front. Diablo is loyal to Rimuru Tempest and currently resides in the Jura Tempest Federation.

Blue Primordial, Bleu
Bleu, now known as Rain, is the Blue Primordial. Despite her composed and beautiful appearance, she dislikes working and often leaves tasks to Vert. Even in the midst of heated battles, Rain tends to complain about various things. She maintains unwavering loyalty to Rouge. Rain is identified by her short blue hair and eyes, and she wears a deep-red maid outfit. Rain is loyal to Guy Crimson and currently resides in the Ice Continent.

Green Primordial, Vert
Vert, now known as Misery, is the Green Primordial. As a maid alongside Rain under Rouge's command, she takes her responsibilities very seriously and dedicates herself entirely to her master. Misery goes to the extent of establishing a cult centered around aiding Rouge's observations of humans. She is characterized by her long, curly green hair and eyes, and she wears a deep-red maid outfit. Misery is loyal to Guy Crimson and currently resides in the Ice Continent.

White Primordial, Blanc
Blanc, now known as Testarossa, is the White Primordial. Despite her gentle appearance, she possesses one of the most terrifying personalities among the Daemons. In the Lake Shore Dyed Scarlet Incident, she massacred an entire city to avenge a friend. After swearing loyalty to Rimuru Tempest, Testarossa gets involved in political manipulations, coercing other members of the Western states council to further her goals. She is distinguished by her silver hair, snow-white skin, and red eyes. Testarossa is loyal to Rimuru Tempest and currently resides in the Jura Tempest Federation.

Purple Primordial, Violet
Violet, now known as Ultima, is the Purple Primordial. Despite her youthful appearance, she takes pleasure in being treated like a princess by her subordinate Daemons. However, she also exhibits a fondness for inflicting pain on others. After being convinced by Noir, Ultima becomes loyal to Rimuru. She can be recognized by her purple hair with a side ponytail and her yellow eyes. Ultima is loyal to Rimuru Tempest and currently resides in the Jura Tempest Federation.

Yellow Primordial, Jaune
Jaune, now known as Carrera, is the Yellow Primordial. Prior to coming under Rimuru's guidance, she had a hobby of sporadically unleashing bursts of Nuclear Magic, often directed towards Leon's capital in El Dorado. Although she has seemingly calmed down since then, those who knew her before still view her as a menace. Carrera is distinguished by her short blonde hair and blue eyes. Carrera is loyal to Rimuru Tempest and currently resides in the Jura Tempest Federation.

Story
Noir was summoned by a woman, one of two members of Silver Wings, who begged him to take revenge on the Arch Daemon Orthos. Noir then hunted down Orthos, fulfilling his contract. In the process of doing that, he met Shizue Izawa and took note of her Anti-Magic Mask that not only blocked one of his attacks but also ended up erasing one of his arms instead. The mask made him very intrigued, so after the incident, he secretly continued observing Shizue until the mask lost its Space-Time attribute when the mask reached Rimuru. Ever since he tried intercepting any Daemon summoning spell performed by Rimuru to get summoned, but the first time Rimuru used it, Noir got one-upped by Beretta instead. But upon Rimuru's second use of Daemon summoning, Noir, as well as two Greater Daemon aides successfully managed to be summoned by Rimuru. Shortly afterwards, Rimuru granted Noir the name "Diablo."

Blanc was the Daemon of note in the Lake Shore Dyed Scarlet Incident. She possessed a young woman by the name of Blanche whom she befriended. Her kingdom had a pact with the Primordial Daemon to one day sacrifice the princess' body to the Daemon as a physical body as long as she kept them safe from other warring nations. This pact was cemented by the crimson eyes of every woman born to the royal family. When the country was destroyed due to schemes of several traitors and the Eastern Empire, Blanche chose to kill herself, which gave Blanc the possession of her body and ownership of her Soul. Blanc then took revenge for her friend causing what would later be known as the "Lake Shore Dyed Scarlet Incident." Then, after a few years passed, Diablo persuaded her to meet Rimuru alongside Jaune and Violet. After meeting Rimuru for the first time, she chose to join Tempest and was granted the name "Testarossa" by Rimuru.

Trivia

 * The nickname of each Primordial is the French word for their respective colors.
 * Primordials were introduced with the Light Novel. This terminology didn't exist in the Web Novel version.
 * Naming a Primordial is risky unless the namer is a Demon Lord (or on the level of one as Rimuru would have been incapable of naming Diablo before becoming a True Demon Lord) or has a surplus of souls to convert into magical energy.
 * Upon reaching Greater Daemon, Daemons are assigned a color that matches one of the Primordials based on their personality. All Daemons of a certain color share the basic personality traits of their progenitor and while they might express these traits in different ways, their demeanor and mindset are always a match for their progenitor.
 * For example Beretta, like Diablo, is polite, reserved, and affable while valuing things beyond strength and having a passion for learning or experiencing new things. Like Diablo, he is absolutely ruthless and unfeeling towards his enemies and can casually eliminate them without ever dropping his polite and affable demeanor.
 * Another example of this is Orthos, who was noted to possess the same prideful, cunning and manipulative disposition as his progenitor, Guy Crimson. This is seen where he showcased enough intelligence and cunning to root himself into human society and obtain his own personal kingdom and create extensive plans in order to further strengthen himself with the majority of the world being oblivious to his machinations, all traits possessed by Guy.
 * According to Misery, Testarossa and Diablo form a troublesome duo.
 * Ultima is the shortest of the Primordials.
 * Each of the Primordials named by Rimuru is named after a supercar - the Lamborghini Diablo, Ferrari Testarossa, Ultima GTR, and Porsche Carrera GT.
 * Similar to the True Dragons, the Primordials cannot permanently die even with the destruction of their Core, but the tradeoff is they will be subordinated to the one that kills them when resurrected.
 * However, there is no compulsion into servitude nor absolute obedience to orders, giving leeway for them to go against their "Master."

Reference
pt-br:Progenitor