Elijah ben Solomon Zalman, (Hebrew: ר' אליהו בן שלמה זלמן Rabbi Eliyahu ben Shlomo Zalman) known as the Vilna Gaon (Yiddish: דער װילנער גאון Der Vilner Gaon, Polish: Gaon z Wilna, Lithuanian: Vilniaus Gaonas) or Elijah of Vilna, or by his Hebrew acronym HaGra ("HaGaon Rabbenu Eliyahu": "The sage, our teacher, Elijah"; Sialiec, April 23, 1720 – Vilnius October 9, 1797), was a Lithuanian Jewish Talmudist, halakhist, kabbalist, and the foremost leader of misnagdic (non-hasidic) Jewry of the past few centuries. He is commonly referred to in Hebrew as ha-Gaon he-Chasid mi-Vilna, "the pious genius from Vilnius".

Through his annotations and emendations of Talmudic and other texts, he became one of the most familiar and influential figures in rabbinic study since the Middle Ages. He is considered as one of the Acharonim, and by some as one of the Rishonim. Large groups of people, including many yeshivas, uphold the set of Jewish customs and rites (minhag), the "minhag ha-Gra", named after him, and which is also considered by many to be the prevailing Ashkenazi minhag in Jerusalem.

Born in Sielec in the Brest Litovsk Voivodeship (today Sialiec, Belarus), the Gaon displayed extraordinary talent while still a child. By the time he was twenty years old, rabbis were submitting their most difficult halakhic problems to him for legal rulings. He was a prolific author, writing such works as glosses on the Babylonian Talmud and Shulchan Aruch known as Bi'urei ha-Gra ("Elaborations by the Gra"), a running commentary on the Mishnah, Shenoth Eliyahu ("The Years of Elijah"), and insights on the Pentateuch entitled Adereth Eliyahu ("The Cloak of Elijah"), published by his son. Various Kabbalistic works have commentaries in his name, and he wrote commentaries on the Proverbs and other books of the Tanakh later on in his life. None of his manuscripts were published in his lifetime.

When Hasidic Judaism became influential in his native town, the Vilna Gaon joined the "opposers" or Misnagdim, rabbis and heads of the Polish communities, to curb Hasidic influence.

He encouraged his students to study natural sciences, and translated geometry books to Yiddish and Hebrew.