Rajesh "Raj" Ramayan Koothrappali, Ph.D. is a fictional character on the CBS television series "The Big Bang Theory". He is played by British Indian actor Kunal Nayyar. He is one out of 4 characters who appear in every episode of the Big Bang Theory (Howard Wolowitz, Leonard Hofstadter and Sheldon Cooper). Raj has a doctorate in astrophysics. His best friend, Howard is an astronaut and has been on the International Space Station (ISS). 