Conrad Mundy is a bad kid who, according to Gretchen, is the second worst kid at Third Street School. As a result of his bad behaviour he is a frequent visitor to Principal Prickly's office. He is also banned from Aaron Kelso's local shop for stealing. In Season Six's "Mundy, Mundy" he decides to become a better person and to do nice things. He is voiced by Warren Sroka.
In the episode "Mundy, Mundy", he prevents a ball from hitting Cindy, Mundy becomes quite popular due to this, much to his chagrin. In the episode "The Girl Was Trouble", Gretchen told him how to get the tissue paper to stick to the ceiling of the bathroom so that, in exchange, he would tell Gretchen to whom he had traded Galileo. In "Gus and Misdemeanors", Mundy, along with his two pals Skeens and Lazy Kid, tricked Gus into stealing. After that, they brought Gus to their secret creek. In "Kurst the Not-So-Bad", Mundy, along with Skeens, Lazy Kid and Sue Bob Murphy, stole huckleberry cobbler from the school cafeteria. Mundy made numerous cameo appearances in several episodes, for instance in the episode "The Madness of King Bob" he was in the angry crowd in front of the playground, he also made a couple of other appearances in the episode "The Ratings Game" at the end of the episode. In one episode called "The Biggest Trouble Ever" he tells T.J. and the gang that he wishes he could have done something so bad that he would've landed on the news.
- Conrad's appearance could be based off Lampwick from Disney's Pinnochio. Both are bucktoothed mischievous redheads.
- Conrad is quite similar to Stuart Dooley from 'King of the Hill'.