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 Margo Harshman Alex Jensen Guest Star Ryan Cartwright Cole Guest Star Chuck Lorre Executive Producer, Writer Bill Prady Executive Producer David Goetsch Writer Anthony Del Broccolo Writer Steven Molaro Writer Jim Reynolds Writer Steve Holland Writer Mark Cendrowski Director