Rajesh Ramayan "Raj" Koothrappali, Ph.D. is a fictional character and one of the protagonists of the CBS television series The Big Bang Theory, portrayed by British-Indian actor Kunal Nayyar. He is one of four main male characters in the show to appear in every episode of The Big Bang Theory, alongside Sheldon Cooper, Leonard Hofstadter and Howard Wolowitz. Raj is based on a computer programmer that the show's co-creator, Bill Prady, knew when he was a programmer.