Johnny Galecki
Leonard Hofstadter (24 eps)
Jim Parsons
Sheldon Cooper (24 eps)
Kaley Cuoco
Penny (24 eps)
Simon Helberg
Howard Wolowitz (24 eps)
Kunal Nayyar
Rajesh Koothrappali (24 eps)
Melissa Rauch
Bernadette Rostenkowski (24 eps)
Mayim Bialik
Amy Farrah Fowler (24 eps)
Carol Ann Susi
Debbie Wolowitz (voice) (8 eps)
Kevin Sussman
Stuart Bloom (6 eps)
Casey Sander
Mike Rostenkowski (2 eps)
Michael J. Massimino
Michael J. Massimino (2 eps)
Wil Wheaton
Wil Wheaton (2 eps)
Joshua Malina
President Siebert (2 eps)
Peter Onorati
Angelo (1 eps)
Blake Berris
Kevin (1 eps)
Courtney Ford
Alice (1 eps)
Becky O'Donohue
Siri (voice) (1 eps)
Vernee Watson-Johnson
Althea (1 eps)
Katie Leclerc
Emily (1 eps)
Robert Clotworthy
Dave Roeger (voice) (1 eps)
Josh Brener
Dale (1 eps)
Lance Barber
Jimmy Speckerman (1 eps)
Jim Turner
Reverend White (1 eps)
Ashley Austin Morris
Laura (1 eps)
Stacey Travis
Sandy (1 eps)
Chriselle Almeida
Lakshmi Choudry (1 eps)
Nick Clifford
Phil (1 eps)
Jonathan Schmock
Jonathan (1 eps)
Karl T. Wright
Jimmy (1 eps)
Jadon Sand
Aaron (1 eps)
Lynn Philip Seibel
Professor Rothman (1 eps)
Dusan Brown
Jeremy (1 eps)
Amy Tolsky
Joan (1 eps)
Endre Hules
Russian Mission Control (voice) (1 eps)
Kevin Brief
Security Guard (1 eps)
Leonard Nimoy
Mr. Spock (voice) (1 eps)
Pasha D. Lychnikoff
Dimitri (1 eps)
Stephen Hawking
Stephen Hawking (1 eps)
Christine Baranski
Beverly Hofstadter (1 eps)