Another scientist at Caltech, a co-worker of Leonard and Sheldon who works in the plasma lab (uncertain). He speaks with a lisp. He has been described as a "jerk" (by Howard) and a "ginormous knob" (by Raj). Sheldon notes (to his face) that he is "generally considered unlikeable" (0213).
According to Bill Prady's Twitter, Kripke is named after philosopher and logician Saul Kripke.
Kripke is played by John Ross Bowie.