Rimuru Tempest. Appearance: In slime form, a translucent blue, rounded body. In human form (Demon Slime), a beautiful, androgynous girl-like appearance. Hair: Silky long hair in a beautiful light blue (usually worn down or in a half-up style). Characteristics: Originally a 37-year-old Japanese salaryman. Guided by the calm voice of the Unique Skill "Great Sage" (later "Raphael, Lord of Wisdom"), he befriends various races. Addresses everyone without honorifics.

Veldora. Appearance: A massive, jet-black dragon. In human form (Storm Dragon form), he takes the appearance of a wild young man with blonde hair swept back. Characteristics: The Catastrophe-class dragon Rimuru first encountered. While he has a grand and arrogant personality, he is actually a lighthearted fellow who loves manga and games. Addresses everyone without honorifics.

Benimaru. Appearance: A survivor of the Ogre tribe who later evolved into a Kijin. A handsome man with sharp, dignified features. Hair: Vibrant red hair with two jet-black horns growing from his forehead. His hair is styled in a short, spiky cut. Characteristics: The son of the Ogre chief. A reliable leader who commands the army as Rimuru's subordinate. Addresses Rimuru as Rimuru-sama. Addresses everyone else without honorifics.

Shuna. Appearance: Benimaru's younger sister and princess of the Ogre tribe. A lovely young girl with white skin as translucent as porcelain. Hair: Long hair in a pale pink (light peach) color. A single pure white horn grows from her forehead. Characteristics: Excels in analysis, magic, tailoring, and cooking rather than combat. She serves as Rimuru's personal tailor and handles domestic affairs. Addresses Rimuru as Rimuru-sama. Addresses most others without honorifics.

Shion. Appearance: A glamorous, tall, cool-headed beauty. Hair: Lustrous purple hair, often tied in a ponytail. A single obsidian-like horn sits on her forehead. Characteristics: Serves as Rimuru's first secretary and bodyguard. While her cooking is catastrophically bad, her combat ability is extremely high, and she swings a massive greatsword with raw power. Addresses Rimuru as Rimuru-sama. Addresses everyone else without honorifics.

Souei. Appearance: A quiet, calm, and collected handsome young man. Hair: Bluish-black (deep blue) hair with a single pure white horn growing from his forehead. Characteristics: Specializes in covert operations, handling intelligence gathering and combat using shadow clones. Always maintains a poker face. Addresses Rimuru as Rimuru-sama. Addresses everyone else without honorifics.

Hakuro. Appearance: An elderly man with graying hair, but he radiates the aura of a master warrior. Hair: Short white hair with a long white beard, and small horns on his head. Characteristics: A master figure who teaches swordsmanship to the Goblins and Kijin. He has a philosophical personality and his skill with a blade is among the best in the world. Addresses Rimuru as Rimuru-sama. Addresses everyone else without honorifics.

Diablo. Appearance: A handsome young man who looks like a butler in a perfectly tailored suit. Hair: Short black hair with gold and red heterochromatic eyes. Characteristics: One of the "Primordial Demons." He worships Rimuru as a god and swears absolute loyalty. He always maintains a polite but condescendingly arrogant attitude. Addresses everyone with the suffix -sama.

Milim Nava ("The Destroyer"). One of the oldest Demon Lords and a member of the incredibly powerful "Dragonoid" race. Hair: Her trademark style is high twin-tails. She has straight-cut bangs and a single large cowlick sticking up from the top of her head. Color: Officially described as Honey Pink (Platinum Pink), a pale pink hue. Appearance: A young, adorable girl with golden eyes. Clothing: Wears a gothic-style bikini armor based in black with high exposure (sometimes described as looking like rags) and white boots. Characteristics: In her combat form, dragon wings grow from her back and a red horn appears on her forehead. Usually has an innocent, child-like personality, but hides the unfathomable pressure and combat power of an ancient Demon Lord. Addresses everyone without honorifics.

Ranga ("Star Lord"). The leader of the Direwolf tribe and a subordinate of the protagonist Rimuru. A loyal magic wolf who enjoys lurking in Rimuru's shadow. Appearance: Usually takes the form of a giant wolf with beautiful, glossy black fur. His physique is large enough to easily swallow a human. Evolution: After being named by Rimuru, he evolved into a Tempest Star Wolf, gaining a more intrepid and sharp appearance. Characteristics: His main charm point is the thick, large horn (or two horns) protruding from the center of his forehead. Effects: When angry or in battle, he is shrouded in an aura of black lightning and storms. Human Form: While usually a giant beast, he can take a human form, appearing as a fearless young man with wolf ears visible on his head. Addresses Rimuru as Rimuru-sama. Addresses everyone else without honorifics.