Chiang Kai-shek (October 31, 1887 – April 5, 1975) was a political and military leader of 20th-century China. He is known as Jiǎng Jièshí (蔣介石) or Jiǎng Zhōngzhèng (蔣中正) in Mandarin.

Chiang was an influential member of the Nationalist Party, the Kuomintang (KMT), and was a close ally of Sun Yat-sen. He became the Commandant of the Kuomintang's Whampoa Military Academy, and took Sun's place as leader of the KMT when Sun died in 1925. In 1926, Chiang led the Northern Expedition to unify the country, becoming China's nominal leader. He served as Chairman of the National Military Council of the Nationalist government of the Republic of China (ROC) from 1928 to 1948. Chiang led China in the Second Sino-Japanese War, during which the Nationalist government's power severely weakened, but his prominence grew. Unlike Sun Yat-sen, Chiang Kai-shek was socially conservative, promoting traditional Chinese culture in the New Life Movement and rejecting western democracy and the nationalist democratic socialism that Sun Yat-sen and some other members of the KMT embraced in favor of a nationalist authoritarian government.