- "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 tall, slim demon. She has short blonde hair, purely white skin, and pink 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.
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 extremely arrogant and cares mostly about her own image, the hottest stories, and the latest gossip.
Killjoy also seems to be homophobic, as she tells Charlie "I don't touch the gays" after she attempts to shake her hand.
Tom is Katie's colleague. It is unclear if their relationship is purely professional or not.
Katie tends to get irritated whenever Tom mentions anything of sexual nature. It is possible that she also has a tendency to abuse Tom, seeing that after Tom makes a pun about "nailing" Cherri Bomb, she is seen pouring scalding hot coffee onto his crotch.
Katie appears to care nothing for Charlie's status as Princess of Hell, believing that she is "too rich and influential" to do so. She has no reluctance whatsoever in talking Charlie down and even threatens to "bury" her.
Katie is doubtful about Charlie's plan to help rehabilitate the denizens of hell, seeing it as a joke and even going so far as to ridicule her during an interview. She additionally fights Charlie after having her pen snatched and being called a bitch.
- Demon Transformation: Killjoy shares the common trait of being able to transform into her Full Demon form, like every other Demon.
- 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 Vivziepop, she sleeps with a lot of men.
|Main characters||Hazbin Hotel||Angel Dust • Alastor • Charlie • Husk • Niffty • Vaggie|
|Helluva Boss||Blitzo • Millie • Moxxie • Loona • Stolas|
|Overlords||Alastor • Lilith • Lucifer • Rosie • Valentino • Velvet • Vox|
|Supporting characters||Baxter • Cherri Bomb • Crymini • Egg Bois • Exterminators • Helsa • Katie Killjoy • Mimzy • Razzle and Dazzle • Seviathan von Eldritch • Sir Pentious • Tom Trench • Travis|
|Others||Arackniss • Barbie Wire • Collin • Eddie • Fat Nuggets • Henroin • Loo-Loo Land Mascot • Molly • Octavia • Roo • Robo Fizz • Tilla • Villa|