Baby Firefly (Sheri Moon Zombie) is the main antagonists of House of 1000 Corpses, and one of the main protagonist villains of The Devil's Rejects and 3 From Hell.
House of 1000 Corpses
The squeaky-voiced, obstreperous, and childlike Baby was probably one of the more comedic characters from the first film. A statuesque beauty with boundless youthful energy, she blended in easily with the outside world, making her the perfect lure for her family's victims. Now 29 years old, Baby had become an expert with firearms and knives. By this point in time, Baby had a criminal record. She was wanted for first-degree murder, armed robbery, grand theft auto, and prostitution.
The Devil's Rejects
Baby's true nature was revealed in the sequel, exhibiting a strong sadistic streak. The sequel also delved into more detail about her relationship with her father, Captain Spaulding (Sid Haig), which was absent from the first film. The two share a deep bond. When they are captured by Sheriff Wydell (William Forsythe), Spaulding tries to take credit for one of Baby's crimes (one involves Mary, one of the earlier victims in the first film) so she won't be tortured.
At the climax of the film, Baby is shot down by the police along with Spaulding and Otis.
3 From Hell