Zhu Xi (Chinese: 朱熹; October 18, 1130 – April 23, 1200), formerly romanized Chu Hsi, was a Chinese calligrapher, historian, philosopher, poet, and politician during the Song dynasty.

Zhu was influential in the development of Neo-Confucianism. He contributed greatly to Chinese philosophy and fundamentally reshaped the Chinese worldview.

His works include his editing of and commentaries to the Four Books, his writings on the process of the "investigation of things" (Chinese: 格物), and his development of meditation as a method for self-cultivation.