The Big Bang Theory co-creator Chuck Lorre revealed his big regret over how he first depicted Kaley Cuoco‘s aspiring actress character Penny, who never even got a last name until she married neighbor Leonard Hofstadter (Johnny Galecki) in season nine of the hit CBS sitcom.

‘We had so many episodes to go before we started to understand that there was a brilliance to Penny’s character that we had not explored,’ the 72-year-old showrunner told The Official Big Bang Theory Podcast on Monday.

‘We did the very cliché in the beginning, you know, goofy blonde who says foolish things. It’s a clichéd character, right? And we missed it. We didn’t have that right away that what she brought to this series, to these other characters, was an intelligence that was alien to them, you know, intelligence about people and relationships and family.’

Chuck continued: ‘It was built in that the scientists of the show didn’t understand how to be with people. She did. She brought a humanity to them that they were lacking and that took a while to figure out. Certainly in the beginning, she was a sadly one-dimensional.’

Way before the 39-year-old California blonde was cast in 2007, Lorre (born Charles Levine) had cast MuchMusic VJ Amanda Walsh to play Katie, ‘a street-hardened tough-as-nails woman with a vulnerable interior’ in the 2006 unaired original pilot.

Unfortunately for the Canadian 43-year-old, the test audience ‘hated’ Katie and her ‘toxic presence’ so the entire pilot was retooled and reshot the next year with new characters Penny, Howard Wolowitz (Simon Helberg), and Rajesh Koothrappali (Kunal Nayyar).