Zhu Jin (朱瑾) (867-918) was a warlord late in the Chinese dynasty Tang Dynasty who would later be a major general of the Wu (also known as Hongnong) state during the subsequent Five Dynasties and Ten Kingdoms period. In the late Tang years, Zhu Jin, as the military governor (Jiedushi) of Taining Circuit (泰寧, headquartered in modern Jining, Shandong) would form a power bloc with his cousin Zhu Xuan the military governor of Tianping Circuit (天平, headquartered in modern Tai'an, Shandong), but they were both eventually defeated by Zhu Quanzhong the military governor of Xuanwu Circuit (宣武, headquartered in modern Kaifeng, Henan). Zhu Xuan was killed, and Zhu Jin fled to the domain of Yang Xingmi the military governor of Huainan Circuit (淮南, headquartered in modern Yangzhou, Jiangsu); he would thereafter serve under Yang and Yang's successors, whose domain formed the Wu state eventually. In 918, angry at the arrogance of the Wu junior regent Xu Zhixun (the son of the regent Xu Wen), he assassinated Xu Zhixun, but Xu Wen's troops attacked him; he committed suicide when he saw that there was no escape.
Zhu Jin was born in 867, during the reign of Emperor Yizong. He was from Xiayi (下邑, in modern Suzhou, Anhui). His older cousin (or, according to some sources, brother)Zhu Xuan was an officer at Tianping Circuit (and would later be military governor), and so he went to serve under Zhu Xuan. He was said to have great ambitions and to be talented in his youth and was the most ferocious warrior in Zhu Xuan's army, but was also said to be violent and cruel.