Zvi Yehuda Kook (1891–1982) was a prominent rabbi and spiritual leader in modern Religious Zionism. Born on 23 April 1891 in Zaumel (now Žeimelis, Lithuania), he immigrated to Jaffa, Ottoman Palestine, in 1904 at age 13 with his family, following his father Rabbi Abraham Isaac Kook's appointment as Chief Rabbi. He was the son of Abraham Isaac Kook, the first Ashkenazi Chief Rabbi of British Mandatory Palestine, and Reiza Rivka Kook (née Rabinowitz-Te'omim). Named after his maternal grandfather Zvi Yehuda Rabinowitz-Te'omim, he married Chava Leah Hutner in 1922; she died childless in 1944, and he remained a widower with no children or documented siblings.

His education included Talmud studies under his father and teachers like Rabbi Reuven Gotfreund and Benjamin Menashe Levin in Latvia, followed by studies at Torat Haim and Porat Yoseph yeshivas in Palestine, Kabbalah with Yaakov Moshe Harlap, philosophy in Germany, and further learning with his father in Switzerland (1915–1916).

Career highlights include editing his father's writings from 1908, teaching at Netzakh Israel school after returning to Palestine in 1920, and serving as administrative director of Merkaz HaRav Yeshiva from 1923, becoming Rosh Yeshiva in 1952 until his death, succeeding Harlap. Under his leadership, Merkaz HaRav became the flagship institution of Religious Zionism.

Ideologically, he co-developed Kookian Zionism with his father, viewing the State of Israel as the beginning of messianic redemption and secular Zionists as divine agents. After the 1967 Six-Day War, he led the Gush Emunim settler movement, encouraging West Bank and Gaza settlements, training militants at the yeshiva, and opposing territorial compromises as treason. Notable students included Rabbis Shlomo Aviner, Zvi Thau, Dov Lior, Moshe Levinger, and Haim Druckman, who founded key settlements.

Controversially described as an ultranationalist fundamentalist, he expressed hostility toward Christianity as idolatry, opposed Western influences like the Gregorian calendar, endorsed force against Arabs denying Jewish land rights (while criticizing their maltreatment), viewed Palestinians as having no national claim, and supported Meir Kahane's Knesset bid with nuances. He famously stated: 'We are not a nation of conquerors. We are returning to the land of our fathers. No one, no prime minister, has the authority to renounce any part of the country. It belongs to the entire people of Israel...'

He died on 9 March 1982 in Jerusalem and is buried in the Mount of Olives Cemetery. His legacy endures as the father of modern Religious Zionism and the settler movement.