The list of “the 100 greatest literary characters” the author refers to can be found here.
Of course all lists are subjective, as Frank has pointed out before. Regarding this list, I'd put together an altogether different rollcall, but mostly, I'd replace Dashiell Hammett's Sam Spade with Raymond Chandler's Philip Marlowe. Marlowe appeared in more novels than Spade's one - The Maltese Falcon - and the Marlowe character appeared in far more films that John Huston's great film adaption of The Maltese Falcon. I think Hammett's Sam Spade, that "Blonde Satan" in the crime novel, is a fine character, but Philip Marlowe is a much more explored and much more influential character. I recall a Dick Cavett from the 1970s where he had on a group of top crime writers that included Ed McBain, P.D. James, Robert Parker and Mickey Spillane, all of whom, save Mickey Spillane, credited Raymond Chandler as their main influence. Spillane, who had been knocked rather harshly in a Chandler novel, cited a comic book writer. (Marlowe had a book that he noted dryly passed for crime fiction these days, clearly a reference to Spillane, and not having a garbage can available, dropped the book in a trash can).Even though Hammett influenced Chandler, I still believe Marlowe is the greater literary character than Sam Spade.
This article is a supplement to The 100 Greatest Literary Characters, a book co-authored by Prof. Plath: “There were at least 50 additional characters that we agonized over but ultimately left out of the book. Below are 10 who deserved to be included but were not.” Philip Marlowe is included in that book for reasons provided on pages 135 through 137.
Dave,Thanks for pointing that out...