Derek is a student in Sheldon's English class who makes fun of Sheldon's use of training wheels (A High-Pitched Buzz and Training Wheels) and the words "tummyache" and "ergo". (A Tummy Ache and a Whale of a Metaphor). Sheldon snaps at him each time in anger at being mocked.
Derek is one of the students who are mad at the Coopers when Sheldon causes a stir on a news program. He calls them traitors, though this backfires to insult Sheldon when a fellow student tells them to go back to Russia. (A Loaf of Bread and a Grand Old Flag).
Derek buys candy from Georgie in "An Entrepreneurialist and a Swat on the Bottom ", though he is grumpy about having to buy two bags.
Sheldon complains to Ms. McElroy about the disparate number of holes on his and Derek's handouts, which riles his teacher but just puzzles Derek. (The Sin of Greed and a Chimichanga from Chi-Chi's)
Derek is portrayed by Nick Alvarez.