Loona is a hellhound with a wolf-like appearance. She has a pointed, dog-like muzzle with sharp and pointy teeth, and a black nose. Her eyes have bright red sclera, white irises, and slit-like pupils. Her fur is white with grey countershading encircling her face, grey patches on her shoulders, and long, hip-length, voluminous silver hair swept to the side to reveal her dark grey ears; one of which is pierced with two small, black hoop-piercings, while the other is ragged. She has a large and long, dark grey bushy tail with white on the underside. She also has a piercing on her right eyebrow with a black hoop for jewelry. Loona is a cynical and choleric young-adult Hellhound, who was adopted from an orphanage by Blitzo when she was nearing eighteen years of age. Loona is lazy and shows little interest in matters that are going on around her. She also has a short-fuse temper and is often rude and apathetic toward her colleagues, particularly Moxxie, though her ire seems otherwise indiscriminate. When not looking at her phone, Loona is usually scowling at anyone in view. Although Loona goes to great lengths to maintain an outwardly apathetic attitude, her troubled and isolated upbringing appears to have made her socially awkward and she admits, in a moment of flustered vulnerability upon meeting another Hellhound, that she does not have any friends. When trying to interact with people she does actually want to connect with, she stumbles over her words and worries over her appearance, Despite her closed off and initially distant nature, Loona actually has a good heart. Although she accompanies the rest of I.M.P.

Blitzo is quite tall for his species, though estimates himself as being roughly four feet tall, and sports a harlequin-like aesthetic. He has red skin with white burn marks of various sizes that cover parts of his forearms, chest, and his tail, as well as most of the right side of his face. His irises are red and he has a heart-shaped skull symbol on the center of his forehead. Blitzo has fairly broad forearms and hands, and a long narrow head, out of which extends large, curved, black and white striped horns. He has black spines on his head and upper back, as well as on his tail. His tail ends with a triangular point that has a black spot at the tip. He has pointed feet with boot-like heels which are shown to have black on the heels and toes areas. Blitzo has red gums. Blitzo is a bombastic, big-talking, and sardonic imp. He is high energy and career-focused, having recently started his own company, something that's noted to be rare for an imp to achieve. He is very invested in the company's success and willing to make many personal sacrifices to achieve it. However, despite his enthusiasm to break out of the lowly social position his species is assigned in Hell. He is also, in many ways, wildly unprofessional and scattershot in his methods. Despite his status as his company's sole director, he can frequently behave in ways that are immature, self-absorbed, and even disrespectful towards his employees, affecting their level of respect for him.

Millie is a short imp with red skin and a rather petite, pear-shaped figure with a long devilish tail. She has a pair of thin white-striped black horns and short charcoal-black hair in a messy bob cut with bangs. Her eyes have yellow sclera and long, thick eyelashes protruding from them, with a small beauty mark under the right eye. Her front teeth have a gap as well. She also has a black heart tattooed on her right shoulder, and makeup which consists of shimmering dark red eyeshadow, thick black mascara, and black lipstick on her lips. She also has two white spots on her upper right arm, two on her lower left arm, two white streaks on her upper left and lower right legs, two white spots on her tail, and one on the tip of her tail. Millie is a very lively and cheerful individual. Often with a smile on her face and rarely standing still, she is a clear extrovert and is not afraid to speak her mind. This is regardless to whether it's expressing her excitement or flipping off a co-worker.

Moxxie is an imp with red skin and white freckles on his cheeks. His white pointy hair leads up to his curvy black and white striped horns. He also has yellow sclera with black slit pupils. He has a long red thin tail with a quadrilateral barb at the end, as well as lanky digitigrade legs ending in what appears to be cloven red hooves, reminiscent of artiodactyls. Moxxie is the I.M.P's weapon specialist; and as such, has a vast knowledge of weapons and often brings a variety of them along during jobs.

Stolas is an anthropomorphic owl demon. He is tall and slender, with a white, heart-shaped facial disk and small black beak, resembling that of an owl. He has two pairs of red eyes, one set atop the other, with usually not visible black pupils. He has gray-blue feathers, which gradients to dark gray-blue on his head and long, plume-like tail. A lighter gray-blue puff of fur is on his chest. He also has a gray streak on his hair. His limbs are long, thin, and black, and his feet are tipped with bird-like claws. Stolas gives the immediate impression of someone regal and ostentatious