Chaim (Haim) Nahum Effendi (Hebrew: חיים נחום; Arabic: حاييم ناحوم) (1872–1960) was a Jewish scholar, jurist, and linguist of the early 20th century. He was born in 1872 in Manisa, Turkey. He was sent by his parents to a yeshiva in Tiberias, after which he studied at a French lycée for his secondary education and obtained a degree in Islamic law in Istanbul. Thereafter, he attended a rabbinical academy in Paris, from which he received his semicha. At the same time, he studied linguistics, history, and philosophy at the Sorbonne's school of oriental languages.
Upon his return to Istanbul, Nahum occupied various teaching positions, including at the Turkish military academy. While there, he became acquainted with many of the leaders of the Young Turk movement, who gained power in 1908.
In 1909 Nahum succeeded Moses Levi as Hakham Bashi, or chief rabbi, of the Ottoman Empire. During the peace negotiations following Turkish War of Independence that followed World War I, Nahum was a member of the Turkish delegation that signed the Lausanne Treaty. For his services to the Turkish government he was given the title of efendi.