Thaddeus "Curly" Gammelthorpe is a fictional character in the Hey Arnold! TV Series. He is a fourth grader who attends P.S. 118. He is in Arnold's class. Curly is most well known for his outlandish and bizarre behavior and freaking out to silly and trivial things (possible symptoms of psychosis or bipolar disorder). He is known as the "fourth grader most likely to snap". He is considered one of the geeks ("Rhonda's Glasses").