Guo Kai 郭開 was a high dignitary in the state of Zhao 趙 during the late Warring States period 戰國 (5th cent.-221 BCE), and a minion of King Daoxiang 趙悼襄王 (r. 245-236) and his successor, King Youmiu 趙幽繆王 (r. 236-228). He was a critical element in the decisive battle between Qin 秦 and the state of Zhao. The commander of Qin, Wang Jian 王翦, bribed Guo Kai to prevent the appointment of the experienced general Lian Po 廉頗 for the forthcoming campaign. Instead, King Youmiu entrusted Li Mu 李牧 and Sima Shang 司馬尚, who offered successful resistance to the approaching army of Qin.
Guo Kai was thereupon instigated by Qin to slander Li Mu by alleging the general planned a rebellion and to defect to the enemy. King Youmiu thereupon ordered to execute Li Mu and dismissed Sima Shang. The two generals were replaced by Zhao Cong 趙蔥 and Yan Ju 顏聚, two unexperienced leaders. Guo Kai is also said to have had contact with Qin during the siege of the capital of Zhao, Handan 邯鄲 (today in Hebei), and helped Qin to conquer the city. Yet instead of rewarding Guo Kai for his collaboration, the Qin commander had Guo killed.