Main Characters
The main characters, Raj, Sheldon, Penny, Leonard, Howard, are the five main characters of the show. Raj Koothrappali is an Indian astrophysicist whose best friend is Howard Wolowitz. He works at Caltech, and his main characteristic is his selective mutism, which does not allow him to talk to women, unless he has been drinking alcohol. Sheldon Cooper is a theoretical physicist who shares a room with his colleague and best friend, Leonard Hofstadter. Sheldon likes to think he is smarter than everyone else, (which he usually is). He is very organized, but he lacks social skills, and does not understand sarcasm and irony very well. Penny is the main female character in the show. She lives across the hall from Sheldon and Leonard in the apartments they live in. She is a waitress at the Cheesecake factory, but lacks education skills. Leonard Hofstadter is an experimental physicist, who also works at Caltech. Him and Penny regularly date in some of the seasons, which is a big part of the show. Howard Wolowitz is an Aerospace Engineer who again, works at Caltech. He is known for wearing vintage 1960s style clothes, and skinny jeans. He tries to hook up with girls with his pick-up lines, but usually fails. Howard lives with his mother, and like all the guys on the show, likes comic books and superheroes.
Sources: Google.com/images
http://en.wikipedia.org/wiki/The_Big_Bang_Theory
http://en.wikipedia.org/wiki/The_Big_Bang_Theory