Barry Kripke, Ph.D. is a Caltech plasma-physicist-turned-string-theorist and an unlikable colleague of Leonard and Sheldon. He has a case of rhotacism, where he pronounces "r" and "l" as "w", much like Elmer Fudd in Looney Tunes. With a knack for ribbing people, he is an on-and-off friend to Sheldon, Leonard, Howard, and Rajesh.