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.

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

The Big Bang Theory may be defying the laws of TV mechanics with its storied success, but there’s one thing co-creator Chuck Lorre said the series “missed” early on with regard to Kaley Cuoco’s character Penny.