Chofetz Chaim
Rabbi Yisrael Meir Kagan better known as the Chofetz Chaim is one of the few latter day Rabbis that have been able to fundamentally awaken people to aspects of Judaism. In his life's accomplishments he added a codex to the Shulchan Aruch and wrote many works on interpersonal/moral laws of the Torah. He is most famous for his book Chafetz Chaim which is the source of his namesake which is a codex relating to Lashon Harah.
This section although under the Halacha category actually contains all his works regardless of type.