- "I'm too rich and influential to give a flying fuck about what a tux-wearing demon princess wants to advertise."
- ―Katie Killjoy, to Charlie
Katie Killjoy is a very tall as well as slim demon. She has short blonde hair, purely white skin, and red eyes with small, yellow pupils. Her most noticeable design traits are her long neck, red lips, big, firm breasts, and wide shoulders. In a shot of the pilot, it is shown that she has a thin waist, along with wide hips. When she moves in a very sudden way, cracking sounds can be heard coming from her body.
In her full demon form, she reveals an extra pair of eyes, which, alongside her original pair of eyes, glow bright red. She also summons two extra pairs of arms that resemble the front legs of a praying mantis right below her usual pair of arms.
Katie is arrogant, selfish, and narcissistic. She scoffed Charlie's plan to rehabilitate demons. Katie cares mostly about her own image, the hottest stories, as well as the latest gossip. She does not care how royal big shot Charlie is, and openly expresses her contempt for her and her ventures. She's also shown to be quite homophobic since she would not even shake hands with Charlie, saying she does not touch the gays because she has standards.
Katie is quite aggressive and seems to always be on edge, she deliberately spills hot coffee on Tom and also insults and threatens Charlie. At the same time, Katie does not tolerate insults in her direction, and when Charlie calls her a bitch, Killjoy instantly falls into a rage and rushes at the princess with her fists.
- Demon Transformation: Killjoy has the ability to transform into a more demonic form when angered.
- Regeneration: She may have an incredible regenerating factor, as when she rushed to her seat after publicity, she snapped her neck, exposing the bone. However, she simply yanked her head back in place, leaving no trace of injury.
- Hand-to-Hand Combat: Killjoy is shown to go all out whenever she engages in hand-to-hand combat. Her skills are well known by Trench as he quickly escapes the scene after Charlie angers her.
- Her last name, Killjoy, means "a person who deliberately spoils the enjoyment of others through resentful or overly sober behavior."
- According to Vivienne, she sleeps with a lot of men.
- Killjoy seems to be homophobic, as she tells Charlie "I don't touch the gays" after she attempts to shake her hand.
- It is possible that Killjoy's personality and appearance may have been inspired after Brandon Rogers character, Bryce Tankthrust.
|Main characters||Hazbin Hotel||Charlie • Vaggie • Angel Dust • Alastor • Husk • Niffty|
|Helluva Boss||Blitzo • Millie • Moxxie • Loona • Stolas|
|Overlords||Alastor • Rosie • Valentino • Velvet • Vox|
|Supporting characters||Baxter • Cherri Bomb • Crymini • The Egg Bois • Exorcists • Helsa • Katie Killjoy • Lilith • Lucifer • Mimzy • Razzle and Dazzle • Seviathan • Sir Pentious • Tom Trench • Travis|
|Others||Arackniss • Barbie Wire • Collin • Eddie • Fat Nuggets • Fizzarolli • Robo Fizz • Henroin • Loo Loo • Martha • Mrs. Mayberry • Molly • Octavia • Ralphie • Roo • Stella • Tilla • Villa • Wally Wackford|