Kaley Cuoco
Herself - Host / Penny (archive footage)
Johnny Galecki
Himself - Host / Leonard (archive footage)
Chuck Lorre
Himself (archive footage)
Jim Parsons
Sheldon / Himself (archive footage)
Kunal Nayyar
Raj / Himself (archive footage)
Mayim Bialik
Amy / Herself (archive footage)
Melissa Rauch
Bernadette / Herself (archive footage)
Simon Helberg
Howard / Himself (archive footage)
Brian Posehn
Bert (archive footage)
John Ross Bowie
Kripke (archive footage)
Kevin Sussman
Stuart (archive footage)
Rati Gupta
Herself (archive footage)
Wil Wheaton
Wil Wheaton (archive footage)
Carol Ann Susi
Mrs. Wolowitz (voice)
Christine Baranski
Beverly (archive footage)
Katey Sagal
Susan (archive footage)
Keith Carradine
Wyatt (archive footage)
Laurie Metcalf
Mary (archive footage)
Adam West
Adam West (archive footage)
Bill Gates
Bill Gates (archive footage)
Billy Bob Thornton
Dr. Oliver Lorvis (archive footage)
Bob Newhart
Arthur Jeffries (archive footage)
Buzz Aldrin
Buzz Aldrin (archive footage)
Elon Musk
Elon Musk (archive footage)
Frances H. Arnold
Frances H. Arnold (archive footage)
George F. Smoot
George F. Smoot (archive footage)
James Earl Jones
James Earl Jones (archive footage)
Joe Manganiello
Joe Manganiello (archive footage)
Kip Thorne
Kip Thorne (archive footage)
Mark Hamill
Mark Hamill (archive footage)
Stephen Hawking
Stephen Hawking (archive footage)
Steve Wozniak
Steve Wozniak (archive footage)
William Shatner
William Shatner (archive footage)