Katie Killjoy is the head anchor of 666 News, Hell's premier news station. She is a background character in Hazbin Hotel. She serves as the secondary antagonist in the pilot. The well accepted theory is that Katie died by committing suicide by hanging herself in 1992 in her 40's, which is why her neck appears elongated and makes disturbing snapping noises whenever she turns or tilts her head.

When she died and went to hell, he was reborn as a demon, with the body of an spider humanoid, similar to but more concealed than Angel Dust. 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.

Like all demons, Katie Killjoy has a full demon or true form, and is one of the few characters thus far to have revealed it and the range of its abilities. 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. This form grants her increased size, strength, and speed; the ability to cling to walls, and increased proficiency in hand to hand combat.

Katie is a very arrogant and selfish. 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.

Katie is quite aggressive, she deliberately spills hot coffee on Tom Trench 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.

Katie Killjoy identifies as Straight, she is explicitly homophobic, and refuses to touch Charlie since she knows she is in a relationship with another woman. She is also known to sleep a lot of men.