Johnny Galecki Leonard Hofstadter Actor Jim Parsons Sheldon Cooper Actor Kaley Cuoco Penny Actor Simon Helberg Howard Wolowitz Actor Kunal Nayyar Raj Koothrappali Actor Mayim Bialik Amy Farrah Fowler Actor Melissa Rauch Bernadette Rostenkowski Actor Kathy Bates Mrs. Fowler Guest Star Teller Mr. Fowler Guest Star Neil deGrasse Tyson Himself Guest Star Bill Nye Himself Guest Star Giovanni Bejarano Bellman Guest Star Ciara Renée Sunny Morrow Guest Star Andy Kim Tour Guide Guest Star Chuck Lorre Executive Producer, Writer Bill Prady Executive Producer Steven Molaro Executive Producer Eric Kaplan Writer Tara Hernandez Writer Steve Holland Writer Maria Ferrari Writer Jeremy Howe Writer Mark Cendrowski Director