Leonard Hofstadter
Johnny Galecki
Sheldon Cooper
Jim Parsons
Penny
Kaley Cuoco
Howard Wolowitz
Simon Helberg
Raj Koothrappali
Kunal Nayyar
Amy Farrah Fowler
Mayim Bialik
Bernadette Rostenkowski
Melissa Rauch
Mrs. Fowler
Kathy Bates
Stuart Bloom
Kevin Sussman
George
Jerry O'Connell
Janine Davis
Regina King
Beverly Hofstadter
Christine Baranski
Arthur Jeffries
Bob Newhart
Young Sheldon
Iain Armitage
President Siebert
Joshua Malina
Dr. Koothrappali
Brian George
Larry Fowler
Teller
Kripke
John Ross Bowie
Neil deGrasse Tyson
Neil deGrasse Tyson
Zack Johnson
Brian Thomas Smith
Wil Wheaton
Wil Wheaton
Wyatt Teller
Keith Carradine
Dr. Pemberton
Sean Astin
Debbie Wolowitz (voice)
Carol Ann Susi
Bert Kibbler
Brian Posehn
Dr. Campbell
Kal Penn
Tam
Robert Wu
George Sr.
Lance Barber
Dr. Park
Eddie Shin
Himself
Kevin Smith
Doctor Lee
Maribeth Monroe
Bill Nye
Bill Nye
Georgie
Montana Jordan
Himself
William Shatner
Nathan
Andy Daly
Andrea
Alison Martin
Bebe
Brooke Dillman
Maritza
Angela Lin
Halley Wolowitz (voice)
Pamela Adlon
Marissa
Lindsey Kraft
Anu
Rati Gupta
Denise
Lauren Lapkus
Karen
Chasty Ballesteros
Jess
Caleb Pierce
Greg
Shay Ali
Terry
Elijah Isaiah Cook
Neil
Eric Nenninger
Danny
Jason Kravits
Waiter
Matt Knudsen
Cynthia
Hira Ambrosino
Mitch
Todd Giebenhain
Himself
Joe Manganiello
Andy
Joel McCrary
Judge
Kurt Scholler
Bellman
Giovanni Bejarano
Trina
Mimi Gianopulos
Himself
Kip Thorne
Greg
Luis Aldana
Sunny Morrow
Ciara Renee
Dr. Graybel
David Theune
Colin
Hermie Castillo
Himself
George F. Smoot
Bob
Chip Chinery
Kwame
Andre Boyer
Himself
Kareem Abdul-Jabbar
Linda
Minerva García
Leslie
Kikey Castillo
Tour Guide
Andy Taylor Kim
Darren
Ben Rauch
Herself
Frances H. Arnold
Tour Guide
Andy Kim
Tour Group Member
Louis C. Robins
Stephen Hawking
Stephen Hawking
Althea
Vernee Watson-Johnson
Richard Williams
Dean Norris
Mike Rostenkowski
Casey Sander
Michael J. Massimino
Michael J. Massimino
Claire
Alessandra Torresani
Eric Gablehauser
Mark Harelik
Announcer (voice) / Man / Man V.O. (voice)
Ed Lieberman
Dimitri
Pasha D. Lychnikoff