Iain Armitage and Raegan Revord, the young leads of Young Sheldon, did not watch The Big Bang Theory before joining the spin-off due to their ages. Armitage, cast at 8, and Revord, at 9, relied on scripts and guidance from Jim Parsons. Despite this, they successfully portrayed the characters in the prequel series.
Young Sheldon, a spin-off of The Big Bang Theory, explores the childhood of Sheldon Cooper, originally played by Jim Parsons. Iain Armitage took on the role of young Sheldon at age 8, facing the challenge of not having seen the parent series. In a 2018 interview with IANS, Armitage explained, "Well, [The 'Big Bang Theory'] isn't really appropriate for me, plus it's not really aimed at my audience level." He had only viewed a few clips and received coaching from Parsons, whom he described as "a very fun guy and very nice," helping him grasp the character quickly.
Raegan Revord, who played Sheldon's twin sister Missy, joined at age 9 and also had not watched The Big Bang Theory. In a 2024 interview with CinemaBlend, she said, "When I [first] did the show, I mean, I was 9 years old. 'Big Bang' is not for a 9-year-old, so I've never seen it before, and I actually still haven't seen it. I probably should watch it at some point."
The popularity of The Big Bang Theory led to multiple spin-offs, including Young Sheldon, which itself inspired Georgie and Mandy's First Marriage. Another project, Stuart Fails to Save the Universe, is in development at HBO Max. Armitage made a cameo in the final season of The Big Bang Theory, appearing in an old video watched by Parsons' Sheldon in the episode "The VCR Illumination." Revord reprised her role as Missy in six episodes of Georgie and Mandy's First Marriage.
Beyond this universe, Armitage has voiced young Shaggy in Scoob! and Chase in The Paw Patrol Movie. He also appeared in the first two seasons of the HBO series Big Little Lies, with stars like Reese Witherspoon, Nicole Kidman, and Meryl Streep, and is set to return for its third season.