Dexter Thornhill, played by Robert Laughlin, is Steve's rival similar to Cassie Lynn Nubbles was to Laura Winslow. He was a Caucasian nerd who went out of his way to outdo him in everything. His only appearance was in Season 5 episode "Presumed Urkel," where Steven is accussed of blowing up the school's science lab just before a competition that he and Thornhill were to take part in. In the upcoming student trial where Steven is to be expelled from school if found guilty, Thornhill is the prosecutor and calls in the science teacher, Mr. Sweeney, and Carl. However, the former states while the last person he saw in his room before the explosion was Steve, he never actually saw the explosion and thus, does not know who really caused it. Carl states that while Steve has done catastrophic damag