Virtually all aspects and periods of the history of Jewish humor have been studied repeatedly, often at length, from the Bible to the Talmudic period to the present day. Two areas where historians of Jewish humor have not dared to tread are medieval Jewish philosophy and Kabbalah. And this for good reason: the medieval Jewish philosophers and kabbalists were very serious thinkers, intent on guiding their readers to conjunction with God and ultimate spiritual happiness. Yet occasionally humor is found in these writings, at times hidden in recondite texts. The present chapter will uncover and, where necessary, explain these examples of humor in medieval Jewish philosophy and Kabbalah. The chapter will also illustrate literary genres of the medieval thinkers—including philosophers—where humor can be found more openly.