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

Chuck Lorre knows Penny was "one-dimensional" and "clichéd" in the early days of the hit sitcom, but after several episodes he realized "there was a brilliance" to her.

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