Keiji Nishitani (西谷 啓治, Nishitani Keiji^?, February 27, 1900 - November 24, 1990) was a Japanese philosopher of the Kyoto School and a disciple of Kitaro Nishida. In 1924 Nishitani received a Ph.D. from Kyoto University for his dissertation Das Ideale und das Reale bei Schelling und Bergson. He studied under Martin Heidegger in Freiburg from 1937-9.

He held the principal Chair of Philosophy and Religion at Kyoto University from 1943 until becoming Emeritus in 1964. He then taught philosophy and religion at Otani University. At various times Nishitani was a visiting professor in the United States and Europe.

According to James Heisig, after being banned from holding any public position by the United States Occupation authorities in July 1946, Nishitani refrained from drawing "practical social conscience into philosophical and religious ideas, preferring to think about the insight of the individual rather than the reform of the social order."

Because the nature of Nishitani's philosophy was expressed more religiously and subjectively, he felt ideologically closer to the existentialists and the mystics, namely Søren Kierkegaard and Meister Eckhart, than to the scholars and theologians who were aimed at more objectively expressing their ideas. Nishitani, "the stylistic superior of Nishida," brought Zen poetry, religion, literature, and philosophy organically together in his work to help lay the difficult foundations of breaking free of the Japanese language in a similar way as Blaise Pascal or Friedrich Nietzsche. Furthermore, unlike Nishida, who had focused on building a philosophical system and who, towards the end of his career, began to focus on political philosophy, Nishitani focused on creating a standpoint "from which he could enlighten a broader range of topics," and wrote more on Buddhist themes towards the end of his career.