The final scene from the finale of “Young Sheldon.”

“Young Sheldon,” the coming-of-age sitcom focused on the childhood of Sheldon Cooper, the egotistical and socially awkward theoretical physicist memorably portrayed by Jim Parsons in “Big Bang Theory,” is coming to a close. The series premiered in fall 2017, becoming the No. 1 new comedy that season, and remained one of the network’s strong performers throughout its run. It even spawned a spin-off, “George & Mandy’s First Marriage,” which will launch this fall. (The series centers on Sheldon’s brother, George Cooper Jr., a.k.a. Georgie (Montana Jordan) and Mandy McAllister (Emily Osment) as they build a life together in 1990s Texas.)