Millie

Millie is a main character in Helluva Boss. She is the bruiser of Immediate Murder Professionals (I.M.P.) a startup assassination business that carries out its services in the living world.

Appearance
Millie is a red demon with a long, demonic tail with white markings. She has eyes made up of yellow scleras and black pupils. She has long black eyelashes that extend beyond the sides of her hair.

She has two black horns with 3 thin white stripes and greyish-black hair with a white splotch in the center and bangs that cover half of her right horn. She has a beauty mark on her left cheek and a gap between her front teeth.

Her attire consists of black lipstick, a simple black choker, a cold-shoulder black crop top with gold buttons where the straps at the top meet the torso piece, torn black pants, fingerless black gloves, and black footwear that does not cover her hoof-like toes.

Millie also has a black tattoo in the shape of a heart on her left shoulder, and two white splotches on the insides and outsides of each of her elbows.

Personality
Millie is very lively and cheerful. Often with a smile on her face and rarely standing still, she is a clear extrovert and isn't afraid to speak her mind. Whether it's expressing her excitement or flipping off a coworker.

Also, as Millie is the bruiser of Blitzo's employees and seems to enjoy her job, it can be assumed she's tough and very violent as well. According to Moxxie, she is aggressive in the sack as well as her job.

Blitzo
Blitzo is Millie's boss. He is the founder and manager of Immediate Murder Professionals. Millie works as his bruiser alongside her husband, Moxxie, who is his weapons specialist. Millie seems to not mind Blitzo's invasive actions and appears to like her boss.

Moxxie
Moxxie is Millie's husband and co-worker. They have a positive relationship and both adore each other. Moxxie even dedicates a song called "Oh Millie" to her, which can be seen at the end of the pilot.

Loona
Loona and Millie don't seem to get along, as in the pilot Millie can be seen flipping Loona off after Loona insults Moxxie.