Dr. Leonard Leakey Hofstadter
Leonard Leakey Hofstadter, Ph.D.is an experimental physicist at the California Institute of Technology, who shares an apartment with his friend Sheldon Cooper. Originally from New Jersey, he attended Princeton University and was 24 when he received his doctorate and won the "Dissertation of the Year for Experimental Particle Physics" award. Despite this breakthrough he is mocked by Sheldon again and again.
In spite of some initial difficulties living together with Sheldon they became friends. However, the gentle Leonard can sometimes be very quick tempered. He often finds himself obliged to explain Sheldon's behaviour or to act as a mediator between Sheldon and other people. Compared to the other characters, Leonard often appears to be the most down-to-earth and most socially competent of the group, although he too shows a strong interest in science fiction and comics and has a huge collection of comics, memorabilia and action figures. Leonard suffers from lactose intolerance which is a recurrent theme throughout the series.
One of his greatest desires is a strong and intimate realtionship with a female character. In the course of the series he finds one or another partner. At first he had brief relationships with the physicist Dr. Leslie Winkle and the physician Dr. Stephanie Barnett. At the begining of the third season he finally started dating Penny. But this relationship does not last either and is over at the end of the same season. After this separation Leonard finds comfort when he dates Raj's sister Priya in the fourth season. After the successful lawyer Priya returns to her home and cheats on Leonard, he breaks up with her in the fifth season. Another relationship between Leonard and Penny takes its course. When he proposes to her at the end of the fifth season, she rejects him though.
The Leonard's family is very elitist. Sheldon always envies him this family environment.
Both of Leonard's siblings are also very intelligent. He had stood in their shadow in the past and he has not yet managed to cope with this.
His father is an anthropologist and his mother is engaged in psychoanalysis and neurology. The emotionally cold mother, Beverly Hofstadter, had guest appearances in the second and third seasons.
Leonard himself now and then repeats his disappointment with his mother who has never given him the desired recognition and mother's love. That's why he had to build a hugging machine that took him in its arms when he was a child.