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 Edwin "Buzz" Aldrin Buzz Aldrin Guest Star Janelle Marra Claire Guest Star Chuck Lorre Executive Producer, Writer Bill Prady Executive Producer Eric Kaplan Writer Jeremy Howe Writer Steven Molaro Writer Steve Holland Writer Maria Ferrari Writer Mark Cendrowski Director