So about Dresden and Hats. The story goes that for the first few novels, the illustrator added a hat because they thought it would add a sense of noir and mystery. Jim Butcher never wanted a hat on the cover because Harry never actually wears a hat. So the illustrator started drawing larger and larger hats on Harry in the cover art while Butcher made Harry more and more adamantly anti-hat in the book. It’s a running joke between the illustrator and the author.
Even to the point where one of the villains wears a fedora and Harry basically says “only evil people wear fedoras. This guy is just missing the goatee”