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 Guest Star Dakin Matthews Santa Guest Star Chuck Lorre Executive Producer, Writer Bill Prady Executive Producer Eric Kaplan Writer Steve Holland Writer Steven Molaro Writer Jim Reynolds Writer Maria Ferrari Writer Mark Cendrowski Director