There is a nice list on this website featuring little kids who are killers and they are all great examples. There is another killer kid that should be mentioned; Melissa Graps (VALERIA VALERI) from MARIO BAVA's KILL BABY KILL. Melissa was the daughter of some local hated Baroness and was accidentally killed by a bull during a town festival. The locals were too busy getting plastered and they didn't like the kid, so they ignored her, even when she rang a church bell for help and so she eventually bled to death. Momma Baroness, who happened to be a medium, decided to get revenge on the town by summoning up her dead 7-year-old and having her kill the locals.
The first time Melissa would appear to her victims she would only creep them out. The second time she appeared to them she would force them to kill themselves! She would show up with a mischievous giggle that was years ahead of DR. GIGGLES and there would be P.O.V. shots of her swinging on a swing in the dead of night. One victim, the town inn keeper's daughter, was taunted by the ghost child when Melissa put her hands on her window, placed her face up to it and simply stared at the poor kid!
Of course the teenager knew that she was Melissa's next target so her parents enlisted the help of a local witch who, among other things, flogs the kid with thorny bushes! She also makes the kid wear a ring of barbed wire around her torso to ward off Melissa. The doctor who was sent to town to investigate the suicides finds this out and thinks it's crazy. He removes the barbed wire from the girl and assumes that it is all superstition and that the girl will be alright. WRONG!!! The next night the girl is woken from her sleep and she sees Melissa by the window again. Melissa puts the girl in a trance and she forces her to impale herself with a piece of metal that's sticking out of a wall mounted candle holder. There is another scene where the doctor goes to the Baroness's castle and he runs into the ghost who announces her presence by throwing a bouncing ball down the hallway.
Melissa then tells the doctor her name and runs off giggling down a spiral staircase. The kid has this sadistic look in her eyes. This is seen when she shows up in the closet of the town burgermiester as he's about to give the doctor's new found assistant, a local med student played by ERIKA BLANC of THE DEVIL'S NIGHTMARE fame, a birth certificate showing her who her true parents were (ERIKA is apparently tied in to the killer kid's history).
O.K., I don't want to give much more away, but near the end the doctor and ERIKA go to the Baroness's place and she takes him to Melissa's bedroom which is full of dolls. Well guess who is sitting on the floor with the dolls!
(That repeating room sequence HAD to have inspired DAVID LYNCH when he did that Red Room sequence in the last episode of TWIN PEAKS!)
Creepy kid eh? So there she is. Melissa Graps, creepy killer child who could fit in with all the other Kindertrauma kids who kill!