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"I'm not overreacting, I'm a teenager!"
— Katie Ka-Boom

Katie Ka-Boom is an innocent 16-year-old girl who greatly overreacts to trivially upsetting situations and literally turns into a flaming monster before subsequently exploding, usually leaving the family home in ruins. She is voiced by Laura Mooney.


Being a typical teenage girl, Katie is very overreactive, ill-tempered, and emotionally difficult. When she's in her normal self, she is actually a lovely, innocent, and nice girl. Though when she goes "Ka-Boom" (hence her last name), she turns into any destructive monster, literally.


In human form, Katie is a tall, teenaged female. She appears to be 16 years old and has a blonde bob hairstyle. She wears an off-shoulder white sweater, pink jeggings and white flats. She also wears red lipstick.

In one cartoon, she wears a red top that exposes her stomach with a belly button.

Before she changes into a monster, her eyes glow bright white, her voice gets very deep and she grows. In monster form, she seems to be able to change into many forms. As one monster, she looks like a green monster and her clothes are ragged, but she has also been seen as a fiery monster. More often than not, the transformation is related to the upsetting situation, such as a giant telephone monster when she loses a call, a Big Daddy Roth-esque hot rod monster during a driving lesson, and a monster in a dress for when arguing about Katie's curfew for staying out late during prom night, the one time her parents stood up to her. However, after she explodes, she’s fine and her clothes are unaffected while the surrounding environment is completely ruined. In one cartoon, the monster's stomach became a yellow hypnotize.

Katie doesn't seem to be aware of her exploding and turning into a monster after she has blown up, but she might just not come on it. During her shift, she will deny her family's statements that she‘s a monster, saying "I'm not overreacting, I'm a teenager!". She may have her shift under control in the revival, however, as she quickly turned into her monster form to chase after Chicken Boo after he captured her along with the rest of the Animaniacs cast.


Animaniacs (comic)

Other appearances




Katie's father and mother with younger brother, Tinker.


  • Katie is a parody of She-Hulk.
  • Katie made three cameo appearances in the series.
    • She appeared in one scene as a alien-looking green monster in "The Big Wrap Party Tonight" when Yakko mention some characters names.
    • She (in human form) appeared in one part in the beginning of “The Scoring Session" where Katie is among one of the characters part of the orchestra. When the sub named Neivel Nosenest came, Katie wasn’t seen in the orchestra pit afterwards.
    • In the revival, she appeared in Good Warner Hunting as one of the characters Dr. Walter Grubb captured. She is seen at the end turning into her monster form from her debut episode and joining the characters chasing after their captor.
  • Nicholas Hollander based Katie on his own teenage stepdaughter who would often explode at every little thing that went wrong.
  • Katie Ka-Boom's design was reused in the final episode of The Sylvester and Tweety Mysteries.