Peacock is brash, combative, optimistic, and deeply obsessed with classic cartoons. ​Though superficially rude, loud-mouthed, and quick to resolve conflicts with slapstick violence, her personality stems from a combination of childhood trauma and her love for old-school animation. Despite her abrasive exterior and fractured psyche, she is fiercely loyal to her friends and fellow Lab 8 members, treating them like family and protecting them at all costs.

Andy Anvil is a prominent, cartoonish character in Skullgirls who functions as one of Peacock’s imaginary friends and summonable gang members. ​Physically, Andy is a literal, personified blacksmith anvil. He features a wide cartoon mouth filled with sharp, shark-like teeth, a pair of expressive eyes, and muscular arms and legs. His visual aesthetic is heavily inspired by classic 1930s rubber-hose animation, sports, and boxing gear, typically appearing shirtless with red boxing gloves, red athletic shorts, long white socks, and red sneakers. ​Personality-wise, Andy is hot-tempered, intensely loyal to Peacock, and deeply passionate about sports, particularly boxing and professional wrestling. In battle, he serves as a physical projectile and melee assist, dropping from the sky or lunging forward to deliver heavy punches and crushing blows to opponents. Conceptually, his design was created by Peacock's imagination based on her memory of the Lab 8 scientist Stanley Whitefin.

Dr. Avian is the benevolent head scientist and director of Anti-Skullgirl Lab 8 in the Skullgirls universe. Distinct from the colder, more ruthless scientists in other laboratories, Dr. Avian acts as a genuinely compassionate, fatherly figure to his subjects, rescuing gravely injured individuals and upgrading them into biomechanical Anti-Skullgirl soldiers. Visually, he appears as a pale, older man with albino traits, including stark white hair and piercing red eyes, often wearing a lab coat and glasses. He is responsible for rebuilding Patricia into the cartoonishly lethal Peacock using the Argus System and Avery Unit, as well as saving the beaten police officer Ben Birdland by reconstructing him into the brass-heavy cyborg Big Band. His death at the hands of Valentine during an attack on Lab 8 serves as a pivotal tragic event in the storyline, driving the motivations of characters like Peacock and Big Band to avenge him.

Big Band is a heavy tank character in the fighting game Skullgirls. Real name Benjamin "Ben" Birdland, he is a former New Meridian police officer who was brutally beaten by corrupt colleagues and rebuilt as a jazz-themed cyborg by the Anti-Skullgirl Labs. Visually, he wears a large trenchcoat over a massive mechanical body containing various musical instruments like saxophones, brass knuckles, and trumpets, allowing him to attack using soundwaves and pneumatic strikes while even letting players play interactive trumpet notes during certain moves. In gameplay, he features high defense, hyper-armor attacks, powerful parry mechanics, and immense reach, balanced by his slow speed and large hurtbox that makes him vulnerable to extended combos.