Spotting 'Moby Dick' or 'Billy Budd' in a crossword always makes me smirk. It's like the puzzle maker is checking if you paid attention in high school English. Beyond those obvious ones, 'Typee' and 'Omoo' pop up surprisingly often, but only in grids where the constructor really wants to trip people up. I've seen 'Bartleby' once, which was a clever but brutal clue.
Honestly, 'Moby Dick' is the workhorse. It fits so nicely with its four and three-letter structure, so it slides into puzzles all the time. The whale's name itself, 'Ahab', is almost as common, and 'Pequod' shows up now and then. If you see a clue referencing whaling or obsession, your pencil should be heading for those squares.