Johnny Galecki Leonard Hofstadter Actor Jim Parsons Sheldon Cooper Actor Kaley Cuoco Penny Actor Simon Helberg Howard Wolowitz Actor Kunal Nayyar Raj Koothrappali Actor John Ross Bowie Barry Kripke Guest Star Carol Ann Susi Debbie Wolowitz Guest Voice Melissa Rauch Bernadette Rostenkowski Guest Star Katee Sackhoff Katee Sackhoff Guest Star Ira Flatow Ira Flatow Guest Star Chuck Lorre Executive Producer, Writer Bill Prady Executive Producer Maria Ferrari Writer Richard Rosenstock Writer Jim Reynolds Writer Steve Holland Writer Mark Cendrowski Director