A wonderful and engaging
logician. His gift of making
logic accessible brings to mind
John Allen Paulos'
Innumeracy, his seamless interweaving of puzzle and story
Martin Gardner's
Doctor Matrix character.
His best work (popularly published book, anyhow; I'm sure his more formal works in academia could be considered more impressive), in my opinion, is Alice through the needle's eye. It's a satisfying alice story quite on it's own, and full of novel and intriguing puzzles.