Guo Si, also known as Guo Duo, was a Chinese military general, politician, and warlord serving under the warlord Dong Zhuo during the late Eastern Han dynasty of China. He assisted Dong Zhuo in his many campaigns and served as a subordinate of Dong Zhuo's son-in-law, Niu Fu, after Dong Zhuo relocated the imperial capital to Chang'an. He later became one of the de facto regents of Emperor Xian, wherein they occupied the capital and held the emperor and imperial officials hostage. However, his downfall came when he quarrelled with his co-regent, Li Jue. He and Li Jue were ultimately defeated by Yang Feng and Dong Cheng, who assisted the emperor to flee the capital. Guo Si was eventually betrayed and murdered by one of his subordinates.

Dong Zhuo, courtesy name Zhongying, was a Chinese military general, politician, and warlord who lived in the late Eastern Han dynasty. At the end of the reign of the Eastern Han, Dong Zhuo was a general and powerful minister of the imperial government. Originally from Liang Province, Dong Zhuo seized control of the imperial capital Luoyang in 189 when it entered a state of turmoil following the death of Emperor Ling of Han and a massacre of the eunuch faction by the court officials led by General-in-Chief He Jin.