Leonard Hofstadter

Leonard is a senior experimental physicist at the California Institute of Technology and has been published in several peer-reviewed journals. His honors include the Newcomb Medal. When he started at the university seven years ago as of the third season, he conducted classified government research on military rocket fuel capable of generating over 8,000 kN of thrust. His work often includes the use of high-powered lasers, and his research topics have varied from Bose-Einstein condensates and fundamental tests of quantum mechanics to cosmic radiation and dark matter. According to Sheldon, most of his work is extremely derivative. Although Leonard feels at home with his geek colleagues, he is reluctant to let others know about his recreational activities (such as Klingon Boggle), as he does not like to be seen as a geek and wants to be more social. Sweet, thoughtful, kind, intelligent, mature, sardonic and socially awkward, but well-meaning, Leonard also seems to be the most well-adjusted and sensible one of The Social Group, and is quick to try new things apart from his geek friends. A lifetime of being denied and refused praise and acclaim that he unavoidably deserves (Because his mother had absolutely little regard or admiration for him and often demolished his infrequent moments of happiness as a child, and Sheldon relentlessly unknowingly demoralizes him and his accomplishments out of egomania and sheer apathy) has led to Leonard yearning for recognition for his intelligence, compassion and determination.Despite his attempts to reject his geek status, Leonard owns, among other things, Star Wars hygiene products, an expensive Superman comic book collection, a "Battlestar Galactica" Colonial warrior's flight suit, and a light saber that he calls a "glow stick".

Leonard is indicated to be proficient in literature, history, and music as well as the sciences - he is able to solve a woman's crossword puzzle in a matter of seconds (the answers were mostly literary in nature) and he can play the cello. Leonard has a lot of conditions. He is lactose intolerant, asthmatic, bespectacled due to myopia, prone to carsickness and migraines, gets a bloody nose after jogging, suffers from sleep apnea, allergies and a lot of ear infections, and possesses a genetic predisposition to heart disease. Leonard's primary health concern is his lactose intolerance. Leonard is somewhat neurotic, insecurely tilting his head as he speaks nervously, as well as avoiding eye contact and squinting. When under great stress, his voice is elevated to a high-pitched whine, when he lies or gets sweaty. At times, Leonard's demeanor seems very low energy and somewhat irritable. Clumsy, he often bangs his head, which induces vomiting. Leonard is incredibly sensitive about his height (he stopped growing in eighth grade), although he enjoys pointing out that Howard is shorter.

Leonard is usually seen wearing his characteristic black-framed glasses, neutral-colored jackets or vests over a hoodie, low-cut black Converse sneakers, brown trousers, and physics-themed t-shirts. Leonard is a short and a little thick man, and in his late twenties. He is 5' 5" (1.65 m) with brunette hair and brown eyes.