Emperor Tongzhi (1856–1875), born Zaichun, was the ninth emperor of the Manchu-led Qing Dynasty, and the eighth Qing emperor to rule over China, from 1861 to 1875.

The only surviving son of the Emperor Xianfeng and the Empress Dowager Cixi, Tongzhi attempted political reform in the period of the Tongzhi Restoration. His first reign name was Qixiang, but this name was later abandoned by Cixi in favour of Tongzhi, a contraction of the classical phrase tonggui yu zhi, which means "to reform/restore together a state of order", although it has been interpreted as "to rule the state with a united mother/son team", which fits the description, as his mother, Empress Dowager Cixi, wielded the real power and ruled behind the scene. The traditional Chinese political phrase "attending audiences behind a curtain" chui lian ting zheng, which had already been used earlier in Chinese history, was used to describe Cixi's rule through her son, the Tongzhi Emperor. The phrase can still be heard in contemporary Chinese politics.

Tongzhi became emperor at the age of five when his father, the Emperor Xianfeng died. His birth mother, Empress Dowager Cixi, his father's Empress, the Empress Dowager Ci'an, and his uncle, Prince Gong, became regents after removing the former regent, Sushun.

Tongzhi married Lady Alute from a Mongol clan and died of smallpox at the age of 18. He was buried in the Eastern Qing Tombs in Hebei province. He had no sons to succeed him. Folklore says that Tongzhi died from a sexually transmitted disease, specifically syphilis, due to his alleged affairs with prostitutes outside of the palace, and that the smallpox diagnosis was given only because the mere discussion of sexually transmitted diseases in China was taboo. However, no credible evidence exists to substantiate the rumours.

His mothers, the two dowagers, resumed regency after appointing 1st Prince Chun's son, Guangxu, his reigning title.