Who played Sheldon Cooper in the CBS television series "The Big Bang Theory"?

Sheldon Lee Cooper Ph.D., Sc.D., is a fictional character in the CBS television series The Big Bang Theory and its spinoff series Young Sheldon, portrayed by actors Jim Parsons in The Big Bang Theory and Iain Armitage in Young Sheldon (with Parsons as the latter series' narrator). For his portrayal, Parsons has won four Primetime Emmy Awards, a Golden Globe Award, a TCA Award, and two Critics' Choice Television Awards. The character's childhood is the focus of Young Sheldon: the series' first season is set in 1989 when nine-year-old prodigy Sheldon has skipped ahead five grades, to start high school alongside his elder brother.

The adult Sheldon is a senior theoretical physicist at The California Institute of Technology (Caltech), and for the first ten seasons of The Big Bang Theory shares an apartment with his colleague and best friend, Leonard Hofstadter (Johnny Galecki); they are also friends and coworkers with Howard Wolowitz (Simon Helberg) and Raj Koothrappali (Kunal Nayyar). In season 10, Sheldon moves across the hall with his girlfriend Amy (Mayim Bialik), in the former apartment of Leonard's wife Penny (Kaley Cuoco). He has a genius-level IQ, but displays a fundamental lack of social skills, a tenuous understanding of humor, and difficulty recognizing irony and sarcasm in other people, although he himself often employs them. He exhibits highly idiosyncratic behavior and a general lack of humility, empathy, and toleration.