Shemaryahu Yosef Chaim Kanievsky (Hebrew: שמריהו יוסף חיים קַניֶבסקִי; January 8, 1928 – March 18, 2022) was an Israeli Haredi rabbi and posek. He was a leading authority in Haredi Jewish society on legal and ethical practice. Known as the Gadol HaDor ("greatest of his generation") and the "Prince of Torah", much of his prominence came through Torah education and advice about Jewish law.

Though Kanievsky held no formal community-wide post, he was the de facto head of the Litvak community of Haredi Judaism, revered as a consummate scholar of Jewish law and tradition, with unimpeachable rulings.

Kanievsky was born in Pinsk, then part of Poland, as the eldest son of Yaakov Yisrael Kanievsky and Pesha Miriam, sister of Avrohom Yeshaya Karelitz. His father served as his sandek at his brit milah (circumcision) and named him Shmaryahu Yosef Chaim, after both his grandfathers: Shmaryahu Yosef Karelitz, the rabbi of Kosava, and Chaim Peretz Kanievsky. On 1 Nisan 1934, he emigrated with his family to Mandatory Palestine, and they settled in Bnei Brak. Initially, the family resided with his uncle, Avrohom Karelitz, and later moved to an adjacent apartment in the Givat Rokach neighborhood. When Karelitz moved to Zikhron Meir, the Kanievsky family also relocated to be close to him.

He studied at the "Rabbi Akiva – Center" Talmud Torah and at the age of ten began attending Tiferet Tzion Yeshiva in Bnei Brak, where he studied under Michel Yehuda Lefkowitz. After six years of study at Tiferet Tzion, his father requested he study at Yeshivat Beit Yosef (Bnei Brak), where he learned the Talmudic tractate Yevamot for one semester. He later transferred to Lomza Yeshiva in Petah Tikva, under the leadership of Reuven Katz. At the age of 16.5, the head of the yeshiva testified to his extensive knowledge of three orders of the Talmud, "with foundational and comprehensive understanding of the Rishonim and Acharonim." In his first year there, at age 17, he completed the entire Babylonian Talmud for the first time. For two years, he attended lectures by Elazar Shach and also learned from Eliyahu Eliezer Dessler in his final year, who had become the head of the yeshiva that same year. Each week, he returned home for Shabbat to learn with his uncle Avrohom Karelitz. During his studies at Lomza Yeshiva, the 1948 Arab–Israeli War broke out, and all students were drafted to guard the southern front with sticks and stones only. Shmuel Grossbard, appointed as their commander, instructed him to go up with his Talmud to the top of the hill, where he studied until the fighting ended.

On 7 Kislev 5712 (December 1951), Kanievsky married Batsheva Esther, daughter of Yosef Shalom Elyashiv. The matchmakers were Ben Zion Brook, head of Novardok Yeshiva in Jerusalem, and Avrohom Karelitz, who praised the groom in a letter and titled him "Master of All the Talmud." Reuven Katz officiated the marriage. The couple resided in Petah Tikva for a few months while he continued to study at Lomza Yeshiva. They later moved to Bnei Brak and initially shared an apartment with the families of Nissim Karelitz, Amram Zaks, and Dov Wintroub, with each family occupying a single room and sharing a communal kitchen. Later, they moved to a larger shared apartment with Pinchas Schreiber's family. In Bnei Brak, he studied at the "Ateret Yosef" kollel, which later became known as Kollel Chazon Ish, where he studied for decades.

In the late 1970s, Kanievsky edited the Tevuna commentary on the Jerusalem Talmud by Yitzchak Eizik Krasilschikov.

Although he was a Litvak rabbi, many sought his blessing, a practice more common among Hasidic rebbes. His blessings were famously brief, typically consisting of the words "blessing and success." In the mid-2010s, he even abbreviated it to "BuH" to save time. His blessings were often used to encourage participation in various campaigns, such as fundraising or vaccination drives, in exchange for his blessing. Many stories circulated of the miracles reportedly brought about by his blessings.

He served on the rabbinical committee of Mayanei Hayeshua Medical Center.