Frank Longo is a freelance puzzle creator who lives in Hoboken, New Jersey. He has had more than 3,000 puzzles published since 1993 and written many books for Sterling, including Master Ninja Sudoku, Beyond Black Belt Sudoku, and Beach Blanket Sudoku, as well as crossword books. He is known for being able to produce sudoku that are diabolically difficult, yet fair, requiring the solver to use advanced techniques not found in typical newspaper and magazine puzzles.