John Leighton Stuart (Chinese: 司徒雷登; pinyin: Sītú Léidēng; June 24, 1876 – September 19, 1962) was a missionary educator, the first President of Yenching University and later United States ambassador to China. He was a towering figure in U.S.-China relations in the first half of the 20th century, a man TIME magazine described as "perhaps the most respected American in China." According to one Chinese historian, "there was no other American of his ilk in the 20th century, one who was as deeply involved in Chinese politics, culture, and education and had such an incredible influence in China."

Stuart was born in Hangzhou, China, on June 24, 1876, of Presbyterian missionary parents from the United States. His father was a third-generation Presbyterian minister from a distinguished family in Virginia and Kentucky (cousins included J.E.B. Stuart, John Todd Stuart and Mary Todd). They arrived in China in 1868, one of the first three Presbyterian ministers sent to China from the U.S. and the first Christian minister to preach in Hangzhou. Stuart's mother, Mary Horton (known affectionately as "Mother Stuart" in Hangzhou), founded the Hangzhou School for Girls, one of the first institutions of its kind in China. His mother's family had played a leading role in the American revolution in Boston, where her Yankee brand of Calvinism valued and promoted the education of women. Stuart had three younger brothers, David Todd (1878), Warren Horton (1880) and Robert Kirland (1883).

Although an American by nationality who spoke English with a Southern accent, Stuart considered himself more Chinese than American. He spoke the Hangzhou dialect. At age 11, he left China to live for several years with relatives of his mother in Mobile, Alabama. At 16, he was sent to prep school in Virginia, where his outdated clothing and mid-19th century diction handed down from his missionary family in China made him a target for teasing by classmates. He graduated from Hampden-Sydney College and later Union Theological Seminary in Richmond, Virginia, where he aspired to become a missionary educator, inspired by the influence of Robert Elliott Speer.

In 1904, after his marriage, he returned to China with his wife, Aline Rodd, of New Orleans, and became a second-generation missionary in China. There, he helped to establish Hangchow Presbyterian College, which later became Zhejiang University. Together, they had one child, Jack, who would become a Presbyterian minister also.

In 1908, Stuart became a professor of New Testament Literature and Exegesis at the Nanking Theological Seminary. During his tenure, he published 'Essentials of New Testament Greek in Chinese' and 'Greek-Chinese-English Dictionary of the New Testament' (1918). His missionary work in China was sponsored by U.S. President Woodrow Wilson's church in Washington, D.C., where Stuart preached and visited Wilson in the White House on home leave. Stuart's family had close ties with Wilson's family in Staunton, Virginia, where Stuart's father, John Linton, had been named after Wilson's uncle.

In January 1919, Stuart became the first president of Yenching University. Over the next two decades, he built "the Beijing institution into China's greatest university" according to the historian John Pomfret. He established financial, educational and physical foundations of the institution. He quickly made the university among the top universities, and the leading Christian institution, in China. He developed the Yenching campus (now home to Peking University) in traditional Chinese architectural styles, even though many Chinese faculty preferred a campus more western in design. Stuart's hope was that China would one day absorb the institution as its own, rather than view it as an imposition of cultural imperialism. He also served on the Board of Trustees of Tsinghua University. He forged partnerships between Yenching and Harvard University, and in 1928 helped to create the Harvard–Yenching Institute, an important legacy in cultural exchange. He also formed partnerships with Princeton University, Wellesley College, and the University of Missouri. He cared much about students and teachers and their interactions and is remembered fondly by Yenching alumni for performing their weddings and for hosting an ongoing salon for student intellectuals on campus. Princeton awarded him an honorary doctorate of humane letters in 1933. In 1936, Yenching threw him a 60th birthday banquet, where kitchen and cleaning workers presented him with a plaque to hang above his door that read, "His kindness knows no class boundaries."

After the establishment of the People's Republic of China in 1949, Yenching University ceased to exist. In 1952, Peking University relocated to the Yenching campus and absorbed most of its academic departments while Tsinghua University absorbed other departments. The official Peking University history museum makes no mention of Stuart or the institution's western ties, yet the campus stands as his memorial.

"Stuart was the consummate friend of China," wrote historian John Pomfret. "In the 1910s, he had argued that Americans should educate the Chinese more and proselytize them less. Stuart had been an early advocate of tearing up the unequal treaties with China, calling on the United States in 1925 to take the lead with 'an act of aggressive goodwill." He supported Chinese nationalism. He was sympathetic to students and faculty at Yenching who participated in May Fourth Movement (1919–1921) and May Thirtieth Movement (1925). He favored the Northern Expedition (1926-1927) against the warlord factions in Beijing. He led a protest with Yenching students against the Japanese invasion of Manchuria (1937). When the invaders overran Beijing in 1937, the Japanese ordered Stuart to fly the puppet regime flag at the Yenching University campus and offer his personal "thanks" to the Japanese military for the institution's "liberation". Stuart, well known among Chinese as a man with a strong moral conscience, declined promptly, sending a terse note to the Japanese commander: "We are refusing to comply with these orders." He resisted Japanese aggression in China in his sermons and speeches on campus and in travels throughout the country. After Japan's attack on Pearl Harbor, the Japanese incarcerated Stuart in Beijing for three years and eight months until the war ended.