Johnny Galecki
Leonard Hofstadter (23 eps)
Jim Parsons
Sheldon Cooper (23 eps)
Kaley Cuoco
Penny (23 eps)
Simon Helberg
Howard Wolowitz (23 eps)
Kunal Nayyar
Rajesh Koothrappali (23 eps)
Kevin Sussman
Stuart Bloom (4 eps)
Carol Ann Susi
Debbie Wolowitz (voice) (4 eps)
Wil Wheaton
Wil Wheaton (2 eps)
Lewis Black
Professor Crawley (1 eps)
Elizabeth Bogush
Catherine Millstone (1 eps)
Yeardley Smith
Sandy (1 eps)
Julio Oscar Mechoso
Officer Hackett (1 eps)
Judy Greer
Elizabeth Plimpton (1 eps)
Oliver Muirhead
Professor Laughlin (1 eps)
Danica McKellar
Abby (1 eps)
Kevin Brief
Glen (1 eps)
Ed Lieberman
Announcer (voice) (1 eps)
Ira Flatow
Self (voice) (1 eps)
Marcus Folmar
Security Guard (1 eps)
Molly Morgan
Bethany (1 eps)
Katee Sackhoff
Self (1 eps)
David Trice
Waiter (1 eps)
Zachary Abel
Todd (1 eps)
Stan Lee
Self (1 eps)
Frank Maharajh
Venkatesh Koothrappali (1 eps)
Sarah Buehler
Sarah (1 eps)
Ally Maki
Joyce Kim (1 eps)
Artie O'Daly
Young Man (1 eps)
Andy Mackenzie
Skeeter (1 eps)
Steve Paymer
Judge J. Kirby (1 eps)
Steven Yeun
Sebastian (1 eps)
Lauri Johnson
Mrs. Gunderson (1 eps)
Ajgie Kirkland
Louie (1 eps)
Jen Drohan
Martha (1 eps)
Jason Mesches
Denny (1 eps)
Brian Thomas Smith
Zack Johnson (1 eps)
Christine Baranski
Beverly Hofstadter (1 eps)