Jiang Ziya (fl. 12th century BC – 11th century BC), also known by several other names, was the founding monarch of the Qi state.

He was a military general and strategist who assisted King Wen of Zhou and King Wu of Zhou overthrow the Shang dynasty and establish the Zhou dynasty. Following their victory in the Battle of Muye, he continued to serve as a Zhou minister. He remained loyal to the regent Ji Dan (Duke Wen of Zhou) during the Rebellion of the Three Guards; following the Ji Dan's punitive raids against the restive Dongyi, Jiang was enfeoffed with the land of Qi. He established his seat at Yingqiu (in modern-day Linzi, Zibo, Shandong).

He has been worshipped as a war god since the Han and, especially, Tang dynasties. He is also celebrated in Chinese literature, and is one of the main heroes in the Ming-era Investiture of the Gods.

The first ruler of Qi bore the given name Shang. The nobility of ancient China bore two surnames, an ancestral temple surname and a lineage surname. His were Jiang (姜) and Lü (呂), respectively. He had two courtesy names, Shangfu (尚父; "Esteemed Father") and Ziya (子牙; lit. "Master Ivory, Master Tusk"), which were used for respectful address by his peers. The names Jiang Shang and Jiang Ziya became the most common after their use in the popular Ming-era novel Fengshen Bang, written over 2,500 years after his death.

Following the elevation of Qi to a duchy, he was given the posthumous name 齊太公 Grand or Great Lord of Qi, sometimes left untranslated as "Duke Tai". It is under this name that he appears in Sima Qian's Records of the Grand Historian. He is also less often known as "Grand Lord Jiang" (姜太公; Jiang Taigong), Taigong Wang (太公望), and the "Hoped-for Lü" (Lü Wang; 呂望). as Jiang Ziya was seen as the sage – whom King Wen of Zhou's ancestor Revered Uncle Ancestor Lei (公叔祖類) (also titled 太公 "Great ~ Grand Lord") had prophesied about and hoped for – to help the Zhou prosper.

The last ruler of the Shang dynasty, King Zhou of Shang, was a tyrant who spent his days with his favorite concubine Daji and executing or punishing officials. After faithfully serving the Shang court for approximately twenty years, Jiang came to find King Zhou insufferable, and feigned madness in order to escape court life and the ruler's power. Jiang was an expert in military affairs and hoped that someday someone would call on him to help overthrow the king. Jiang disappeared, only to resurface in the Zhou countryside at the apocryphal age of seventy-two, when he was recruited by King Wen of Zhou and became instrumental in Zhou affairs. It is said that, while in exile, he continued to wait placidly, fishing in a tributary of the Wei River (near today's Xi'an) using a barbless hook or even no hook at all, on the theory that the fish would come to him of their own volition when they were ready. This became a standard reference for later recluses, who might sometimes "fish for fame" instead of "fishing for fish."

According to legend, Jiang Ziya was born into a poor family who left him in the wild to die, but animals cared for him and kept him alive until a noble woman found him. She gave the boy the name Ziya and raised him as her son. By the age of ten, he had already mastered mystical arts, and at eighteen, he set off in search of a master. On the journey, he met a celestial being who told him that his place was not with the immortals. Instead, his destiny was to end the cruel reign of the Shang. Thus, Jiang Ziya returned home to fulfill his destiny.

King Wen of Zhou, (central Shaanxi), found Jiang Ziya fishing. King Wen, following the advice of his father and grandfather before him, was in search of talented people. In fact, he had been told by his grandfather, the Grand Duke of Zhou, that one day a sage would appear to help rule the Zhou state.