Hong Rengan (Chinese: 洪仁玕; pinyin: Hóng Réngān; Wade–Giles: Hung Jen-kan; 1822 – 23 November 1864) was an important leader of the Taiping Rebellion. He was a distant cousin of the movement's founder and spiritual leader Hong Xiuquan. His position as the Prince Gan (干王) resembled the role of a Prime Minister. He is a noted figure in history because of the sweeping reforms attempted under his rule, and because of his popularity in the West.
Hong worked as a village teacher in Guanlubu Village, Hua County, Guangdong. Although educated, he was unable to pass the imperial examinations. He was among the first of Hong Xiuquan's converts. In 1847, he accompanied Hong Xiuquan on his trip to Guangzhou and briefly studied the Bible there with Hong Xiuquan and Issachar Jacox Roberts.
During the early years of the rebellion, Hong was separated from the rebellion and had to flee to Hong Kong, where he met the Swedish missionary Theodore Hamberg and converted to Christianity. He helped with church work for the Basel Mission in Sheung Wan and learned much about Christianity. Hong provided Hamberg with important information on the Taiping rebellion, which Hamberg later used to write a book about the movement, The visions of Hung-Siu-tshuen, and origin of the Kwang-si insurrection, published in Hong Kong in 1854.
Hong also served as an assistant to James Legge, working on translations of Chinese classics into English, and on the Chinese Serial, the first Chinese language newspaper in Hong Kong. During this time he learned much about Western politics, economics, history, geography, astronomy and other sciences.
When Hong Xiuquan called for his cousin Hong Rengan to come to Nanjing to help him rule, the Taiping administration was entrenched in a bitter power dispute. The powerbase of the movement had largely become split between the devout Taiping religious followers in Nanjing and the generals commanding the armies outside the city.