Xiang Yu (c. 232 – c. January 202 BC), born Xiang Ji, was a Chinese warlord who founded and led the short-lived kingdom-state of Western Chu during the interregnum period between the Qin and Han dynasties known as the Chu–Han Contention (206–202 BC). A nobleman of the former state of Chu, Xiang Yu rebelled against the Qin dynasty under the command of his uncle Xiang Liang, and was granted the title of "Duke of Lu" (魯公) by King Huai II of the restoring Chu state in 208 BC. The following year, he led an outnumbered Chu army to victory at the Battle of Julu against the Qin armies led by Zhang Han. After the fall of Qin, Xiang Yu divided the country into a federacy of Eighteen Kingdoms, among which he was self-titled as the "Hegemon-King of Western Chu" (西楚霸王) and ruled a vast region spanning central and eastern China, with Pengcheng as his capital.

Although a formidable warrior and tactician, Xiang Yu was poor in both diplomacy and strategy, especially after dismissing his own adviser Fan Zeng. He was later outcompeted by his main rival Liu Bang during the massive civil war among the rebel kingdoms, which concluded with his eventual defeat and suicide in a last stand at the Battle of Gaixia. The demise of Xiang Yu allowed Liu Bang to subsequently become the founding emperor of the newly established Han dynasty, which is widely regarded as a golden age in Chinese history.

Xiang Yu's family name was Xiang (項) while his given name was Ji (籍) and his courtesy name was Yu (羽). He is best known as Xiang Yu (項羽). Xiang Yu is referred to as the "Hegemon-King of Western Chu" (西楚霸王) or simply "Hegemon-King" (霸王; also translated as "Conqueror-King").

There are two accounts of Xiang Yu's family background. The first claimed that Xiang Yu was from the House of Mi (羋), the royal family of the Chu state. His ancestors were granted Xiang County (項縣; around present-day Shenqiu County, Henan) as their fief by the king of Chu and had since adopted Xiang as their family name. The other account claimed that Xiang Yu was a descendant of a noble clan from the Lu state and his family had served in the Chu army for generations. Xiang Yu's grandfather, Xiang Yan [zh], was a general who was killed in action while leading Chu forces to resist an invasion by the Qin state in 223 BC.

Xiang Yu was born in 232 BC during the late Warring States period when the Qin state started conquering the other six major states. According to the descendants of the Xiang family living in Suqian, Jiangsu, Xiang Yu's father was Xiang Chao (項超), Xiang Yan's eldest son. Xiang Yu was raised by his uncle, Xiang Liang, because his father died early. In 221 BC, when Xiang Yu was about 11 years old, the Qin state unified China and established the Qin dynasty.

Xiang Yu had a double pupil in one eye just like the mythical Emperor Shun and Duke Wen of Jin. He was thus seen as an extraordinary person because his unique double pupil was a mark of a king or sage in Chinese tradition. Xiang Yu was slightly taller than eight chi, or approximately 1.86 m (6 ft 1 in), and possessed great physical strength as he could lift a ding.

In his younger days, Xiang Yu was instructed in scholarly arts and swordsmanship but he did not manage to master what he was taught, and his uncle Xiang Liang was not very satisfied with him. Xiang Yu said, "Books are only useful in helping me remember my name. Mastering swordsmanship allows me to face only one opponent, so it's not worth learning. I want to learn how to defeat thousands of enemies." After hearing that, his uncle tried to teach him military strategy, but he stopped learning after he had grasped the main concepts. Xiang Liang was disappointed with his nephew, who showed no sign of motivation or apparent talent apart from his great strength, so he gave up and let Xiang Yu decide his own future.

When Xiang Yu grew older, Xiang Liang killed someone so they fled to the Wu region to evade the authorities. Around the time, Qin Shi Huang was on an inspection tour in that area. As Xiang Yu and his uncle watched the emperor's procession pass by, Xiang Yu said, "I can replace him." Shocked by what his nephew said, Xiang Liang immediately covered Xiang Yu's mouth with his hand. After this incident, Xiang Liang began to see his nephew in a different light.