Young Sheldon

• Iain Armitage as Sheldon Cooper, a child prodigy with a "once-in-a-generation mind capable of advanced mathematics and science". While well-versed in all types of math and science, he is shown to prefer theoretical physics, stating that he decided to pursue the field around the same time as the show began. While academically gifted, Sheldon lacks a full understanding of social cues and behaviors, in addition to having a sense of superiority over everyone around him due to his intelligence. Sheldon is prone to traveling his own path even if he gets into trouble along the way. Nevertheless, Sheldon has proven to love his family and almost always has his heart in the right place.[2][4] He is age 9 in the first season and age 10 in the second.[5]
• Zoe Perry as Mary Cooper, Sheldon's mother. She is very protective and patient with Sheldon but also struggles to understand him at times. She is a devout Christian and so has friction with Sheldon's atheism and derision of Christianity. Nevertheless, she deeply loves her son and wants to protect him for as long as she can.[4]
• Lance Barber as George Cooper Sr., Sheldon's father and the head football coach at Medford High. George does not share Sheldon's intellect, sometimes leading others, especially Meemaw, to doubt him being Sheldon's father. However, he is often the voice of reason for Sheldon. Though he may struggle with understanding his intellectually gifted son, he is a loving father and has defended Sheldon on multiple occasions, earning Sheldon's love and appreciation.[1][2]
• Montana Jordan as George "Georgie" Cooper Jr., Sheldon's older brother. Georgie detests Sheldon and never hesitates to bully him. He is not very intelligent and so is mocked and teased by the rest of the family, particularly Sheldon and Meemaw. While he is outwardly confident in himself, Georgie hides deep insecurities over feeling inferior to his genius brother and thus copes by trying to belittle Sheldon's intelligence in any way he can. He attends Medford High with Sheldon and plays on the football team.[1][2]
• Raegan Revord as Missy Cooper, Sheldon's fraternal twin sister. She teases Sheldon along with Georgie but not as much. She does not share Sheldon's intelligence but is very perceptive. She does not always get along with Sheldon, but she finds in her twin brother a solid confidant and has admitted to not feeling as whole without him.[1] In episode 21 of season one, she asks her father to call her Melissa, implying that Missy is a nickname.
• Jim Parsons as the voice of adult Sheldon Cooper, who provides the perspective of an adult looking back at his childhood.[1]
• Annie Potts as Constance "Connie" Tucker, Sheldon, Missy, and Georgie's grandmother, whom they refer to as "Meemaw". She is very close with Mary and her grandchildren but does not think highly of George and often jokes about him. She is the most patient and understanding of Sheldon's quirks and advises Mary to trust that Sheldon will find his way.[6]
• Matt Hobby as Pastor Jeff (season 3; recurring seasons 1–2),[7] the upbeat pastor at the Cooper family's church. Like Mary, he has friction with Sheldon's atheism, but he often challenges Sheldon to explore their line of thought through logic exercises. He was originally given the last name Hodgkins, but it was changed to Difford as of the episode "Seven Deadly Sins and a Small Carl Sagan".

• Ryan Phuong as Tam Nguyen, Sheldon's Vietnamese-American childhood best friend and classmate. Tam is responsible for introducing Sheldon to many of his non-scientific interests, including comic books and role-playing games.
• Wallace Shawn as John Sturgis, a college physics professor who is romantically interested in Meemaw with Sheldon's encouragement.
• Wyatt McClure as Billy Sparks, the son of a neighbor to the Cooper family, who is even less intelligent than Sheldon's siblings. He was also Sheldon's nemesis.
• Billy Gardell as Herschel Sparks, Billy's father who owns a garage.
• Melissa Peterman as Brenda Sparks, Billy's mother who works at the bowling alley frequented by Meemaw and Mary's nemesis.
• Doc Farrow as Assistant Coach Wayne Wilkins, Sheldon's P.E. teacher and the assistant football coach at Medford High. He was originally given the name Roy, but it was changed to Wayne as of the episode "A Broom Closet and Satan's Monopoly Board".
• Valerie Mahaffey as Victoria MacElroy, Sheldon's homeroom and English teacher at Medford High.
• Danielle Pinnock as Evelyn Ingram, Sheldon's math teacher at Medford High.
• Brian Stepanek as Hubert Givens, Sheldon's science teacher at Medford High.
• Rex Linn as Tom Petersen, the principal of Medford High.
• Sarah Baker as Sheryl Hutchins, the Medford High librarian.
• Nancy Linehan Charles as Peg, Pastor Jeff's chain-smoking secretary.
• VyVy Nguyen as Trang Nguyen, Tam's mother and Mr. Nguyen's wife.
• Isabel May as Veronica Duncan, Georgie's Halloween date who is introduced in "Seven Deadly Sins and a Small Carl Sagan". She converts to Christianity after seeing the "lust" room in Mr. Lundy's haunted house and loses interest in Georgie, who continues trying to win her over.
• Craig T. Nelson as Dale Ballard, Missy's baseball coach and Meemaw's love interest.[8]
• Chris Wylde as Glenn, the owner of the comic book store King Kong Comics.
• Mckenna Grace as Paige Swanson, a child prodigy whom Sheldon views as his rival.
• Andrea Anders as Linda Swanson, Paige's mother.
• Ed Begley Jr. as Dr. Linkletter, a colleague of Dr. Sturgis. He regularly pursues Connie but is continually rebuffed.
• Mary Grill as Officer Robin, Pastor Jeff's second wife who works as a police officer
• Ava Allan as Jana, Georgie's girlfriend.

• Melissa Tang as Ms. Fenley, a music teacher at Sheldon's high school. Tang had previously played the character Mandy Chao in an episode of The Big Bang Theory.
• Bob Newhart as Arthur Jeffries, a scientist who plays the title character of Professor Proton, Sheldon's favorite educational television series. The character is a homage to Mr. Wizard.[9] Newhart reprises his portrayal of the character from The Big Bang Theory.
• Vernee Watson as Nurse Robinson, a nurse who caters to George when he suffers a mild heart attack and then to Sheldon when he has his gall bladder removed. Watson also plays a nurse named Althea in numerous episodes of The Big Bang Theory, including its pilot.
• John Hartman as Dr. Goetsch, the psychiatrist Sheldon sees when he has Phagophobia and when he loses at the Medford High science fair.
• Ray Liotta as Vincent, Meemaw's bookie.
• Jason Kravits as Dr. Ronald Hodges, a NASA engineer and college roommate of Mr. Givens. He makes a presentation about his work to Mr. Givens' science class, which intrigues Sheldon to solve the challenges of reusable launch systems.
• Elon Musk makes a cameo appearance in the episode "A Patch, a Modem, and a Zantac®" in a flashforward scene set 27 years into the future.
• Dave Florek as Dr. Eberland, Sheldon's doctor.
• Karly Rothenberg as Mrs. Janice Veazey, Dr. Hodges' secretary.
• Frances Conroy as Dr. Flora Douglas, headmaster of the boarding school Sheldon briefly attends.
• Harry Groener as Elliot Douglas, Dr. Douglas' husband.
• Paul Yen as Le Nguyen, Tam's father. He runs Medford Mart with his wife.
• Phil Morris as the voice of One and Anjali Bhimani as the voice of Zero in a dream Sheldon has.
• Richard Kind as Ira Rosenbloom, one of Meemaw's boyfriends.
• Zuleyka Silver as Selena, Pastor Jeff's ex-wife
• Anjelika Washington as Libby, an eleventh grade student who aspires to be a geologist and whom Sheldon and Tam befriend.
• Jason Alexander as Mr. Gene Lundy, Medford High School's resident drama teacher.[10]
• Ella Allan and Mia Allan as Bobbi Sparks, Billy Sparks' younger sister with a reputation for tormenting Sheldon.
• Cleo King as Mrs. Costello, a Medford High School counselor.
• Michael Cudlitz as a NASA supervisor who appears in Sheldon's daydream sequence.
• Josh Cooke as Barry Swanson, Paige's father.
• Ella Anderson as Erica, Paige's sister who bonds with Georgie and Missy, as they share common experiences being siblings of child prodigy.
• Paul Fusco appears as Alf in "A Race of Superhumans and a Letter to Alf" when he reads Missy's letter.[11]
• Mauricio Lara as Ricky, Sheldon's hospital roommate
• John Rubinstein as Rabbi Schneiderman
• Benjamin Stockham as Preston
• Maree Cheatham as Dorothy, Veronica's grandmother.
• Kaley Cuoco as the voice of the pool water in one of Sheldon's nightmares. Cuoco previously played Penny in The Big Bang Theory.[12]
• Diedrich Bader as the voice of Batman in one of Sheldon's daydreams.
• Steve Burns as Nathan
• Reba McEntire as June, Dale's ex-wife.
• Taylor Spreitler as Sam, a member of Sheldon's project group.
• Nolan Bateman as Keith, a member of Sheldon's project group.
• Louie Anderson as Ralph, the owner of a trophy shop where Mary wants to buy one for Missy.
• Cyndi Lauper as Herself, Missy's poster.

In November 2016, it was reported that CBS was in negotiations to create a spin-off of The Big Bang Theory centered on Sheldon Cooper as a young boy. The prequel series, described as "a Malcolm in the Middle-esque single-camera family comedy" would be executive produced by The Big Bang Theory co-creator Chuck Lorre and producer Steven Molaro, with The Big Bang Theory co-creator Bill Prady expected to be involved in some capacity, and intended to air in the 2017–18 season alongside The Big Bang Theory.[15][16] The initial idea for the series came from Jim Parsons (who portrays the older Sheldon on The Big Bang Theory), who passed it along to The Big Bang Theory producers.[4] On March 13, 2017, CBS ordered the spin-off Young Sheldon series, which was created by Lorre and Molaro. Jon Favreau directed and executive produced the pilot. Parsons, Lorre, Molaro and Todd Spiewak also serve as executive producers on the series, for Chuck Lorre Productions, Inc. in association with Warner Bros. Television.[1] On September 27, 2017, CBS picked up the series for a full season of 22 episodes.[17] On January 6, 2018, the show was renewed for a second season.[18] The second season premiered on September 24, 2018.[19] On February 22, 2019, CBS renewed the series for both a third and a fourth season.[20] The third season premiered on September 26, 2019.[21] On March 13, 2020, Warner Bros. Television shut down production on the series due to the 2019–20 coronavirus pandemic.[22]

In early March 2017, Iain Armitage was cast as the younger Sheldon, as well as Zoe Perry as his mother, Mary Cooper. Perry is the real-life daughter of Laurie Metcalf, who portrays Mary Cooper on The Big Bang Theory.[4] Lance Barber stars as George Cooper Sr., Sheldon's father; he had previously appeared in one episode of The Big Bang Theory.[23] Raegan Revord stars as Missy Cooper, Sheldon's twin sister; Revord getting the part only after repeatedly asking her mother to be allowed to read for the role.[24] Also starring Montana Jordan as George Cooper Jr., Sheldon's older brother. Jim Parsons reprises his role as adult Sheldon Cooper, as narrator for the series.[2] In July 2017, Annie Potts was cast as Meemaw, Sheldon's grandmother.[6]

In most cases different actors are used to portray a given character in the two series, to account for the age difference. Jim Parsons is a notable exception in that he appears in both series as the same character, though in this series his appearance is limited to voice only. Bob Newhart appears as Professor Proton in both series; with the appearance in this series the character is made to look younger. Iain Armitage (Sheldon), Lance Barber (George), and Montana Jordan (Georgie) make a guest appearance in the parent series in a scene in which a VHS tape recorded decades earlier is played.[25] There are other actors who appear in both series but as different characters. This includes Barber, who had another guest appearance in the parent series as a different character.[26] Elon Musk makes cameo appearances as himself in both series.[27][28]

The second-season finale episode aired immediately following the one-hour series finale of the parent series. In a tribute to the parent series finale, several references are made to the parent series in the Young Sheldon episode. The references are both general to the entire parent series, as well as to the series finale in particular. In one scene in the Young Sheldon episode, Sheldon promises his father that when he wins the Nobel Prize, Sheldon will mention him in his acceptance speech. In the parent series finale, Sheldon wins the Nobel Prize. In another scene in the Young Sheldon episode, Nobel Prize winners are announced out over a montage showing the main characters from the parent series Leonard, Penny, Raj, Howard, Bernadette and Amy as children. Following the montage, adult Sheldon says that he was wrong about feeling at the moment of the Nobel prize announcement that he would be all alone for the rest of his life.[29]

The review aggregator website Rotten Tomatoes reported a 76% approval rating with an average rating of 6.61/10 based on 45 reviews. The website's consensus reads, "Young Sheldon's appealing cast and relatable themes bring a fresh—and overall enjoyable—perspective to its central character's familiar story."[38] Metacritic, which uses a weighted average, assigned a score of 63 out of 100 based on 25 critics, indicating "generally favorable reviews".[39]