Using the pseudonym Richard Stark, Donald E. Westlake wrote the hardboiled paperback originals about the thief, Parker. They are popular books, and many of the titles have gone through several printings from different publishers. I'm showing covers of some from my bookshelves, and some covers I have found online.
Because some of the titles have undergone changes over the years, due to tie-ins with movies, this bibliography of the Parker novels is useful.
Covers I found online: