Zhu Xi (1130–1200) was the most influential Chinese Neo-Confucian (Daoxue) scholar of imperial China (220 bce–1908 ce). He is ranked the foremost philosopher of China since Mencius and Zhuangzi of Antiquity. His influence spread throughout East Asia, particularly to Korea, Japan, and Vietnam, and it persists to this day. Zhu was a master interpreter of the Confucian classics and the teachings of Confucius and Mencius and their earlier followers. He was such exuberant interpreter of the Confucian classics that he ventured not just to edit and rearrange many of them, but in the case of the Daxue (Great Learning) he interpolated a long paragraph that he himself wrote into the text. He also absorbed the philosophical concepts of the 11th-century Northern Song masters, such as Zhou Dunyi, Zhang Zai, Cheng Hao, and Cheng Yi, and integrated them into a comprehensive system by serious analytic and synthetic thinking. Zhu Xi’s system influenced his interpretive work, while the classics and thinkers he studied afforded him issues, topics, and examples for reflection and developing his system. Zhu had a probing, reflective mind, an analytic and synthetic acumen, and his philosophical inquiries led in every direction: ontology, cosmology, philosophical anthropology, natural philosophy, ethics, politics, epistemology, education, the transmission or succession of the Confucian Way, and so forth, making him the most well-rounded of traditional Chinese philosophers. In his philosophic thinking, Zhu Xi is distinguished for his arguing for determinate, well-defined views based on his system, categories, methodology, and place in the Confucian succession. He was at once a classical interpreter who sought deeper meanings as well as textual mastery and a philosophical thinker who discussed and debated a range of issues with his contemporaries. Many of Zhu’s writings and dialogues have been translated into English and other Western languages. And the body of research on Zhu’s scholarship, classical studies, and philosophical thought East and West is growing apace. The scholarship has evolved from general and philosophical to contextualized and historical. Issues have evolved from his comparability with Plato, Aristotle, and Whitehead to specific characteristics of his thought as transcendental versus immanental, conceptual, or formal versus process. Moreover, his ethical thought is compared with parallel Western approaches and brought to bear on a range of ethical issues.