Katie Ka-Boom is a recurring fictional character in Warner Bros' Animaniacs animated series. Katie is a teenage girl who lives with her family (Mom, Dad, and her little brother) in a suburban house somewhere in the USA. Her main shtick is that she has a very bad temper (much like Stephen King's characters Carrie White and Charlie McGee from Firestarter), and when even the slightest thing goes wrong with her day, she quite literally explodes in a fit of rage, destroying her house and anything around her. Her family is well aware of this and takes cover whenever she's ready to blow.

Originally intended as a one-shot in the "Animaniacs Stew" gag, Katie first appeared in the short "Katie Ka-Boo", alongside Chicken Boo, who was portraying her jock boyfriend C.B. In the end, upon learning the truth about him, she went ka-boom. She came back twenty or so episodes later in "The Driving Lesson" and appeared in a few other five-minute shorts. Her odd affliction was never fully explained (the closest the series ever came was the catchphrase "I'M A TEENAGER!"), and most of the shorts stuck to the same formula, with only a few variations.

Laura Mooney voiced Katie. Her mild-mannered father was voiced by Rob Paulsen as a parody of Jimmy Stewart, and her mother was voiced by Mary Gross.