Maimonides (Moses ben Maimon)

Born in Córdoba, Spain, Maimonides — or Rabbi Moshe ben Maimon — was a busy man. He codified Jewish law (the Mishneh Torah), philosophized about faith and reason (The Guide for the Perplexed), and practiced medicine. All in a day's work, apparently, for a mind that wasn't content with just one monumental achievement.

He fled persecution in his youth, eventually settling in Egypt where he became the personal physician to the Grand Vizier and Sultan Saladin. Imagine being brilliant enough to not only write the book on Jewish law but also to keep the most powerful man in the region from, well, perishing. Talk about job security.

His writings continue to be studied voraciously, proving that some ideas, much like a good kvetch, are truly timeless. Maimonides didn't just understand Judaism; he practically architected it for future generations, making him not just a Jew, but a foundational pillar.