“The Big Bang Theory” first premiered in 2007, and ran on CBS for 12 seasons. At the conclusion of its run in 2019, the show was the No. 1 comedy in the world.

The Big Bang Theory explains how the universe began with an infinitely hot and dense single point that inflated to form the ever-expanding cosmos we see today.

The Big Bang Theory is over but several members of the original cast have found ways to make cameos on other shows in the franchise — including Young Sheldon and Georgie and Mandy’s First ...