Sima Shi (208 – 23 March 255), courtesy name Ziyuan, was a military general and regent of Cao Wei during the Three Kingdoms period of China. In 249, he assisted his father Sima Yi in overthrowing the emperor Cao Fang's regent Cao Shuang, allowing the Sima family to become paramount authority in the state, and he inherited his father's authority after his father's death in 251. He maintained a tight grip on the political scene and, when the emperor, Cao Fang, considered action against him in 254, had him deposed and replaced with his cousin, Cao Mao. This tight grip eventually allowed him to, at the time of his death in 255 after just having quelled a rebellion, transition his power to his younger brother, Sima Zhao, whose son Sima Yan eventually usurped the throne and established the Ji