Thaddeus Gammelthorpe, better known as "Curly," is a fictional nerd with a bowlcut on the Nickelodeon cartoon Hey Arnold!. He usually plays a minor role, but has been the focal point of a few episodes.
Curly is known for being the fourth grader "most likely to snap" by his peers. He has covered himself in war paint and freed animals from the zoo for no particular reason. Curly is a fan of opera and ballet, as seen in several episodes. In "School Play," he was cast as Tybalt in "Romeo and Juliet." He has also pulled the school's fire alarm at least twice.
Curly is essentially a creepy, mentally fragile, nerdy kid. In almost all of his appearances, he is shown to have either gone completely insane over minor problems or drooling over Rhonda, whom he once blackmailed into being his girlfriend.
Like most minor fourth graders on Hey Arnold!, Curly's parents are very rarely shown.
His name is most likely a reference to Curly from the Three Stooges while his hairstyle is like that of Moe.