"The Big Bang Theory" co-creator Chuck Lorre says Kaley Cuoco's character Penny took a few seasons to fully understand. "It's a cliched character: the dumb blonde, and we missed it," Lorre said during the first episode of "The Official Big Bang Theory Podcast.

Prior to Kaley Cuoco, actress Amanda Walsh was cast to play Katie, “a street-hardened tough-as-nails woman with a vulnerable interior.”

Lorre explained that it took the show a while to understand that the character was more than a "dumb blonde" The Big Bang Theory creator Chuck Lorre is looking back on the evolution of Kaley Cuoco’s character in the beloved sitcom’s early days.