The principal cast members of “The Big Bang Theory” are Johnny Galecki, as Caltech physicist Leonard Hofstadter, and Jim Parsons, as Caltech physicist Sheldon Cooper. Other central cast members include Kaley Cuoco-Sweeting, who plays Penny, Simon Helberg, as the aerospace engineer Howard Wolowitz, and Kunal Nayyar, as astrophysicist Raj Koothrappali.
Johnny Galecki heads “The Big Bang Theory” cast alongside Jim Parsons. Born in Belgium to a United States Air Force family and raised in Chicago, Galecki has worked in film with Chevy Chase, Robert Urich and Christopher Walken. Prior to his stint on “The Big Bang Theory,” Galecki appeared in “The Opposite of Sex” and “My Name Is Earl.” Native Houstonian Jim Parsons trained in theatre at the University of Houston and the University of San Diego. After graduation, he moved to New York, where he had a recurring role on “Judging Amy” before being cast as Sheldon.
Californian Kaley Cuoco-Sweeting, who plays their neighbor Penny the waitress, aspiring actress and pharmaceutical rep, has worked as a model and actress since age 6. Her other TV credits include “Ellen,” “Northern Exposure” and “My So-Called Life.” An accomplished character actor and sketch comedian, Californian Simon Helberg, who plays Howard, studied at New York University's Tisch School of the Arts and trained at the Atlantic Theater Company. Indian Kunal Nayyar, who plays Raj, moved to the United States in 1999 to study business. He also holds a Master of Fine Arts from Temple University and has worked with the Royal Shakespeare Company.