Gueststars
- Ryan Phuong as Tam - 28 episodes
- Wallace Shawn as Dr. John Sturgis - 28 episodes
- Wyatt McClure as Billy Sparks - 21 episodes
- Doc Farrow as Coach Bergdoff - 18 episodes
- Brian Stepanek as Mr. Givens - 16 episodes
- Danielle Pinnock as Ms. Ingram - 15 episodes
- Matt Hobby as Pastor Hodgkins - 14 episodes
- Valerie Mahaffey as Ms. MacElroy - 14 episodes
- Rex Linn as Principal Petersen - 12 episodes
- Craig T. Nelson as Dale - 11 episodes
- Melissa Peterman as Brenda Sparks - 11 episodes
- Sarah Baker as Ms. Hutchins - 10 episodes
- Nancy Linehan Charles as Peg - 10 episodes
- Isabel May as Veronica - 9 episodes
- Billy Gardell as Herschel Sparks - 5 episodes
- Ed Begley, Jr. as Dr. Linkletter - 5 episodes
- Ava Allan as Jana - 4 episodes
- Mary Grill as Officer Robin - 4 episodes
- Bob Newhart as Professor Proton - 4 episodes
- Nick Alvarez as Derek - 4 episodes
- Andrea Anders as Linda - 4 episodes
- Mckenna Grace as Paige - 4 episodes
- Katherine Von Till as Local Newscaster - 4 episodes
- Pam Cook as Diane - 3 episodes
- Chris Wylde as Glenn - 3 episodes
- John Hartman as Dr. Goetsch - 3 episodes
- Richard Kind as Ira Rosenbloom - 3 episodes
- London Chesire as Marcus - 3 episodes
- Jason Alexander as Mr. Lundy - 3 episodes
- Josh Cooke as Barry - 2 episodes
- Mac Jarman as Rick - 2 episodes
- Dave Florek as Dr. Eberland - 2 episodes
- Ed Ackerman as Nate - 2 episodes
- Vyvy Nguyen as Trang Nguyen - 2 episodes
- Melissa Tang as Ms. Fenley - 2 episodes
- Vernee Watson as Nurse Robinson - 2 episodes
- Zuleyka Silver as Selena - 2 episodes
- Jack Seavor McDonald as Jared - 2 episodes
- Doug Cox as Pastor Dave - 1 episode
- Paul Yen as Le Nguyen - 1 episode
- Cait Pool as Lisa May - 1 episode
- Cleo King as Mrs. Costello - 1 episode
- Deb Hiett as Susan - 1 episode
- Elon Musk as Himself - 1 episode
- Kiva Jump as Daisy - 1 episode
- Kurt Doss as Ned - 1 episode
- Bill Chott as Franklin - 1 episode
- Dale Raoul as Melissa - 1 episode
- Ian Ousley as Jeremy - 1 episode
- Jim Beaver as Kenneth - 1 episode
- Joe Howard as Edwin - 1 episode
- Lily Keene as Sueann Ludlow - 1 episode
- Megan Park as Francine - 1 episode
- Miller Tai as Clark - 1 episode
- Paul Bates as Luis - 1 episode
- Paul Fusco as Alf - 1 episode
- Quinn Aune as Four-year-old Penny - 1 episode
- Ray Liotta as Vincent - 1 episode
- Scott Peat as Gerome - 1 episode
- Alex Staggs as Stan - 1 episode
- Chris Ellis as Marty Steinbecker - 1 episode
- Emily Berry as Janice - 1 episode
- Ethan Stern as Nine-year-old Howard - 1 episode
- Franco Vega as Agent #1 - 1 episode
- Heather Olt as Waitress - 1 episode
- Ivan Mallon as Tim - 1 episode
- Jayne Taini as Phyllis - 1 episode
- John Eddins as Paramedic - 1 episode
- Jordan Leer as Bryan - 1 episode
- Josh Latzer as Hank - 1 episode
- Kirk Bovill as Actor #1 - 1 episode
- Nick Carson as Pat Culpepper - 1 episode
- Rich Grosso as Croupier - 1 episode
- Ryan Stiles as Dr. Bowers - 1 episode
- Steve Burns as Nathan - 1 episode
- Tate Berney as Dexter - 1 episode
- Tim Griffin as Clint Watson - 1 episode
- Travis Guba as Pete - 1 episode
- Ava Cantrell as Molly - 1 episode
- Barry Corbin as Mr. Gilford - 1 episode
- Becki Dennis as Mary-Sue - 1 episode
- Casey Childs as Receptionist [voice] - 1 episode
- Cooper North as Student - 1 episode
- Cyndi Lauper as Herself [v.o.] - 1 episode
- David Fennoy as Thoth - 1 episode
- Forrest Dean as Jason - 1 episode
- Isaac Harger as Eight-year-old Leonard - 1 episode
- J. Rene Pena as Caroline - 1 episode
- James Sklena as Detention Student #1 - 1 episode
- John Mariano as Richard Feynman [v.o.] - 1 episode
- Joy Jacobson as Actress - 1 episode
- Kevin D'Arcy as DMV Employee - 1 episode
- Kirt Kishita as Japanese Dad - 1 episode
- Magnus Chhan as Student - 1 episode
- Pamela Adlon as Mrs. Wolowitz (O.S.) - 1 episode
- Parker Daily as Five-year-old Sheldon - 1 episode
- Phil Hendrie as Albert Einsten [v.o.] - 1 episode
- Ryan Cargill as Tommy - 1 episode
- Shane Blades as Actor #2 - 1 episode
- Susan Chuang as Dr. Barrett - 1 episode
- Tiffy Jeneen as Shopper #1 - 1 episode
- AJ Coggeshall as Five-year-old Bernadette - 1 episode
- Adam Kulbersh as Fred Murphy - 1 episode
- Alref Woodley as Shawn - 1 episode
- Amanda Payton as Meredith - 1 episode
- Carol Mansell as Mrs. Krawcynski - 1 episode
- Cedric Begley as Doug - 1 episode
- Corwin Allard as Luke - 1 episode
- Davey Johnson as Nigel - 1 episode
- David Theuene as Scientist - 1 episode
- Ella Anderson as Erica - 1 episode
- Eloise Jacott as Robin - 1 episode
- Gerald Downey as Jim - 1 episode
- Harry Groener as Elliot - 1 episode
- Jason Kravits as Dr. Hodges - 1 episode
- Kate Flannery as Nora - 1 episode
- Kerri Medders as Lisa - 1 episode
- Kurt Koehlher as Nurse Pryor - 1 episode
- Kurt Scholler as Stan - 1 episode
- Livia Trevino as Paula - 1 episode
- Martin Garcia as Mr. Nelson - 1 episode
- Mauricio Lara as Ricky - 1 episode
- Monica Garcia as Coughing Teacher - 1 episode
- Nolan Bateman as Keith - 1 episode
- Phil Morrison as One - 1 episode
- Piort Michael as Emergency Alert (V.O.) - 1 episode
- Reba McEntire as June - 1 episode
- Wiley Pickett as FBI Agent #1 - 1 episode
- Aaron Schwartz as Marcus - 1 episode
- Alexander Arzu as Mikey - 1 episode
- Aliyah Moulden as Pepper - 1 episode
- Amy Farrington as Dr. Sandra Thorpe - 1 episode
- Anjali Bhimani as Zero - 1 episode
- Annelise Grace as Abby - 1 episode
- Carlease Burke as Mrs. Ebner - 1 episode
- Carol Ann Susi as Mrs. Wolowitz (O.S.) - 1 episode
- Charlie Hankin as Randall - 1 episode
- Chris Flanders as Gary - 1 episode
- Daniele Lawson as Shelby - 1 episode
- Dennis Cockrun as Mr. Strover - 1 episode
- Diedrich Bader as Batman - 1 episode
- Frances Conroy as Flora - 1 episode
- Hilda Boulware as Judy - 1 episode
- Isaac Faulkner as Party Guy - 1 episode
- Isabella Coben as Nell Cavanaugh - 1 episode
- Kerry O'Malley as Fran - 1 episode
- Louie Anderson as Ralph - 1 episode
- Maree Cheatham as Dorothy - 1 episode
- Melanie Haynes as Felicia - 1 episode
- Nick Armstrong as Patron - 1 episode
- Sara Sanderson as Leslie - 1 episode
- Stacey Moseley as Carol - 1 episode
- Angelina Nguyen as Kim-Ly Nguyen - 1 episode
- Brandon Morales as Referee - 1 episode
- Bryce McBratnie as Elliot - 1 episode
- Cheyenne Nguyen as Mai Nguyen - 1 episode
- Christopher Cho as Omar - 1 episode
- David Futernick as Man in Crowd - 1 episode
- Jason E. Kelley as Moving Guy - 1 episode
- John Rubinstein as Rabbi Schneiderman - 1 episode
- Jonathan Brooks as Radio DJ (V.O.) - 1 episode
- Jonney Ahmanson as Bruce - 1 episode
- Lily Sanfelippo as Eleven-year-old Amy - 1 episode
- Michael Cudlitz as NASA Director - 1 episode
- Rishabh Prabhat as Nine-year-old Koothrappali - 1 episode
- Rodney J. Hobbs as Marcus - 1 episode
- Shanon Ferguson as Madam Laveau - 1 episode
- Stone Eisenmann as Detention Student #3 - 1 episode
- Wallace Langham as Dr. Edward Pilson - 1 episode
- Wayne Wilderson as Dr. Gilbert - 1 episode
- Brielle Barbusca as Cheerleader - 1 episode
- Christian Garcia as Stinson - 1 episode
- Hannah Eisenmann as Detention Student #4 - 1 episode
- Karly Rothenberg as Mrs. Veazey - 1 episode
- L. Emille Thomas as Umpire - 1 episode
- Lanisa Frederick as Cashier - 1 episode
- Leonard Robinson as FBI Agent #2 - 1 episode
- Marcia Ann Burrs as Woman at Church - 1 episode
- Patricia Belcher as Clara - 1 episode
- Taylor Spreitler as Sam - 1 episode
- Yennifer Behrens as Teresa - 1 episode
- Zoran Radanovich as Russian Dad - 1 episode
- Amanda Pearl Bell as Vanessa - 1 episode
- Arriane Alexander as Customer #2 - 1 episode
- Benjamin Stockham as Preston - 1 episode
- Duane Shepard Sr. as Mr. Bustifer - 1 episode
- Jay Brian Winnick as Shopper #2 - 1 episode
- Karen Constantine as Lorraine - 1 episode
- Robert Clotworthy as Mayor Harrison - 1 episode
- Thomas Adoue Polk as Dave - 1 episode
- Winifred Freedman as Luann - 1 episode
- Aaron D. Alexander as Customer #1 - 1 episode
- Caitlyn Carmicheal as Veronica - 1 episode
- Caleigh Kilpatrick as Abigail Barker - 1 episode
- Christine Baranski as Beverly Hofstadter (O.S.) - 1 episode
- Ella and Mia Allan as Bobbi Sparks - 1 episode
- Gabriella Martinez as Kate - 1 episode
- Parker James Logie as Young Georgie - 1 episode
- Anjelika Washington as Libby - 1 episode
- Catherine H. Fisher as July - 1 episode
- Chelsea Rae Bernier as Lynette - 1 episode
- Christopher Griffin as Detention Student #2 - 1 episode
- J. Anthony McCarthy as Butcher - 1 episode
- Murray Wyatt Rundus as Clint - 1 episode
- Corey Mendell Parker as Customer - 1 episode
- Lyn Alicia Henderson as Sally - 1 episode
- Michael C. Alexander as Greg - 1 episode
- Christopher Carrington as Dealer - 1 episode
- Christian Benz Belnavis as Customer #1 - 1 episode