Who is the illustrator of the hardy boys books?

Answer 1

There have been many different illustrators over the years, but the name of the book's illustrator may be found on the copyright page. See the links below for more info about HB cover art.

Answer 2

The original illustrator of the Hardy Boys series was Franklin W. Dixon, which was actually a pseudonym used by multiple ghostwriters. Later editions of the books have been illustrated by various artists.