Stephen Sondheim is a master of wordsmithing, and that made him a great candidate to write crossword puzzles [Blog post with links]. But not just any sort of crossword puzzles. [How To Do A Real Crossword Puzzle, NY Mag. Archive link] His cryptic crosswords continue to be a bane to crossword lovers.
An additional link in this post is The Sondheim Puzzle by Frank Rich in NYMag, 2013. It has nothing to do with crosswords.
Oh, and just for the truly interested, look I made a hat!