"We did the very clichéd, in the beginning, goofy blonde who says foolish things," Lorre says of the character Penny.

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.

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