Johnny Galecki Leonard Hofstadter Actor Jim Parsons Sheldon Cooper Actor Kaley Cuoco Penny Actor Simon Helberg Howard Wolowitz Actor Kunal Nayyar Raj Koothrappali Actor Melissa Rauch Bernadette Rostenkowski Actor Mayim Bialik Amy Farrah Fowler Actor Kevin Sussman Stuart Actor Carol Ann Susi Debbie Wolowitz Guest Voice Pasha D. Lychnikoff Dimitri Guest Star Michael J. Massimino Mike Massimino Guest Star Jan Hoag Lillian Guest Star Ken Lerner Dr. Schneider Guest Star John Mendoza Chauffeur Guest Star Chuck Lorre Executive Producer, Writer Bill Prady Executive Producer, Writer Jim Reynolds Writer Anthony Del Broccolo Writer Steven Molaro Writer Eric Kaplan Writer Mark Cendrowski Director