Lloyd Jensen, played by Evan Matthew Cohen, is one of Malcolm and Stevie's Krelboyne classmates, and best friend for the first four seasons of the show. Lloyd is portrayed as nerdy, physically and emotionally frail, and overly dramatic. As a Krelboyne, Lloyd is often bullied by his fellow classmates, including Reese, and often suffers the consequences of schemes with which he helps Malcolm, much like the relationship Francis and Eric have. He mentions to have a unnamed sister.
Lloyd suffers from anger displacement tendencies and major self esteem issues, which he regularly sees the school therapist, Mrs. Gilbert, for. He has been publicly humiliated several times, most famously during Krelboyne Picnic in which his braces get stuck to an extremely powerful magnet he built. It is lightly hinted that he is suicidal,as stated by Dabney, that the majority of his plans end in suicide,and that he has made a death pact more than once. In Cynthias Back, he mentions he has a third nipple. Like Malcolm's other Krelboyne friends he appears less frequently during season 4, eventually leaving only Stevie as his friend. Interestingly, Lloyd is an undergraduate house at Caltech, a university well known for its emphasis on the natural sciences and engineering. He also has mentioned an unnamed sister.
In Season 3's Cliques, after an experiment gone wrong, the Krelboynes had to temporaily return to mainstream education. Lloyd fitted in with the Goth clique after reciting a line from book Dante's Inferno and eventually becomes their leader.