Emperor Guangwu of Han (Chinese: 漢光武帝; 15 January 5 BC – 29 March AD 57), personal name Liu Xiu (劉秀), courtesy name Wenshu (文叔), was the founding emperor of the Chinese Eastern Han dynasty. Through the Eastern Han's suppression and conquest of regional warlords, the dynasty's rule over the whole of China proper was consolidated by the time of Emperor Guangwu's death in AD 57. During his reign, Taoism was made the official religion of the Eastern Han, and the Chinese folk religion began to decline.

Liu Xiu was one of the many descendants of the Western Han imperial family. Following the usurpation of the throne by Wang Mang and the ensuing civil war during the disintegration of Wang's Xin dynasty, he emerged as one of several descendants of the fallen dynasty claiming the imperial throne. After assembling forces and proclaiming himself emperor in the face of competitors, he was able to defeat his rivals, destroy the peasant army of the Chimei, known for their disorganization and marauding, and finally reunify China in AD 36.

He established his capital in Luoyang, 335 kilometers (208 mi) east of the former capital Chang'an (modern Xi'an), ushering in the Eastern Han (Later Han) dynasty. He implemented some reforms (notably land reform, albeit not very successfully) aimed at correcting some of the structural imbalances responsible for the downfall of the Former/Western Han. His reforms gave a new 200-year lease of life to the Han dynasty. His reign was sometimes referred to as the "resurgence of Guangwu" (光武中兴); the capable rule of his son Emperor Ming and grandson Emperor Zhang was referred to as the Rule of Ming and Zhang.

Emperor Guangwu's campaigns featured many able generals, but he lacked major strategists. That may very well be because he himself appeared to be a brilliant strategist; he often instructed his generals on strategy from afar, and his predictions generally would be accurate. This was often emulated by later emperors who fancied themselves great strategists but who actually lacked Emperor Guangwu's brilliance—usually to disastrous results.

Also unique among emperors in Chinese history was Emperor Guangwu's combination of decisiveness and mercy. He often sought out peaceful means rather than bellicose means of putting areas under his control. He was, in particular, one rare example of a founding emperor of a dynasty who did not kill, out of jealousy or paranoia, any of the generals or officials who contributed to his victories after his rule was secure.

Liu Xiu was the sixth generation descendant of Emperor Jing of the Western Han dynasty. He was the son of Liu Qin (劉欽), magistrate (縣令 i.e., head official) of Nandun County (南頓縣), near present-day Xiangcheng, Henan. Liu Qin was the son of Liu Hui (劉回), vice governor in charge of military affairs for Julu Commandery (鉅鹿都尉). Liu Hui was the son of Liu Wai (劉外), governor of Yulin Commandery (鬱林太守). Liu Wai was the son of Liu Mai (劉買), known posthumously as Marquess Jie of Chongling (舂陵節侯). Liu Mai was the son of Liu Fa (劉發), known posthumously as Prince Ding of Changsha (長沙定王). The Prince of Changsha was a brother of Emperor Wu, a famous emperor of the Former Han and the son of Emperor Jing and Lady Tang. As a descendant of Liu Fa, this also made Liu Xiu third cousin to the Gengshi Emperor.

Liu Qin was married to the daughter of one Fan Chong (樊重), and he and his wife had three sons – Liu Yan, Liu Zhong (劉仲), and Liu Xiu. Liu Qin died early, and the brothers were raised by their uncle Liu Liang (劉良). Liu Yan was ambitious, and ever since Wang Mang usurped the Han throne in AD 8 and established the Xin dynasty, Liu Yan was constantly considering starting a rebellion to restore the Han dynasty. Liu Xiu, in contrast, was a careful man who was content to be a farmer. However, his brother-in-law Deng Chen (鄧晨), the husband of his sister Liu Yuan (劉元), who believed in a prophecy that a man named Liu Xiu would be emperor, constantly encouraged him to be more ambitious.

In AD 22, with virtually the entire empire rebelling against Wang Mang's incompetent rule, Liu Yan prepared his rebellion. He planned, along with his brothers, and Li Tong (李通) and his cousin Li Yi (李軼), to kidnap the governor for Nanyang Commandery (roughly modern Nanyang, Henan) and call for the people of the commandery to join him. When the young men of their home territory of Chongling heard about the rebellion, they were all scared to join—until they saw that Liu Xiu was part of the rebellion as well, figuring that if even a careful man like Liu Xiu was part of the rebellion, the rebellion was carefully planned.