Anne Hathaway plays the superhero's feline adversary in upcoming sequel The Dark Knight Rises, but Nolan has confessed he wanted to abandon the idea until his screenwriter sibling Jonathan Nolan talked him round.
He tells Empire magazine, "Catwoman is a very iconic figure in the Batman pantheon. I was nervous about how she would fit into our world. But (Jonathan) was very much convinced that there would be a way to do it and eventually turned me around.
"Once I got my head around the idea of looking at that character through the prism of our films, saying, 'Who could that person be in real life?' we figured it out."
Jonathan Nolan adds, "You've got to have her, because she has a delicious greyness to her that helps define who Batman is."