Penny was originally named Katie.
Penny’s character was actually the last lead to be developed after the creation of The Big Bang Theory. And in the first pilot, she was named Katie and was played by actress Amanda Walsh. You may remember Walsh from Disturbia, Ghosts of Girlfriends Past and Beauty & The Briefcase. Walsh was later replaced by Kaley Cuoco in the second pilot, which then also featured the new name for the character.