Dark Stanley (also and formally known as Stanley Degroot) was once a cook at Springfield Elementary School as well as a One-Time antagonist.
According to Bart, children mocked Stanley for never having graduated from MIT. Eventually, he snapped from anger and murdered the children with a cleaver. From their heads he made "Kid's Head Soup" and remarked that it needed "more girl".
Executed for the crimes and buried in an unmarked grave, the following day, the entire cemetery was missing. After Bart told the story, rumors about Stanley quickly spread.
It was suggested by another psychologist that Stacey Swanson was using Bart to replace her son, who was murdered by Dark Stanley.
Behind the Laughter
Although initially implied to be a fictional story told by Bart, it was later implied to be true, as another psychologist stated that Stacey Swanson's son was killed by Stanley.