Raymond Smullyan was a man who wrote books and made puzzles that made people really use their brains and think hard. He liked to tell stories that had a lot of hidden meanings and tricks in them, so that people had to figure out what was really going on.
He was so good at making brain teasers, that some people called him a "logician", which means he studied how we think and how we use reason to solve problems. He also liked to play with symbols and numbers, kind of like puzzles, to see how they fit together and what patterns they make.
Even though he died a few years ago, many people still enjoy his books and puzzles today, because they are still fun and challenging to solve. They are like a really hard game for your brain!