Sima You

Sima You (Chinese: 司馬攸; pinyin: Sīmǎ Yōu; 246¹ – 27 April 283²), courtesy name Dayou (大猷), posthumously known as Prince Xian of Qi (齐献王), was an imperial prince of the Western Jin dynasty of China. He was the second son of Sima Zhao, a regent of the Cao Wei state during the Three Kingdoms period, and Zhao's wife Wang Yuanji. His wife was a daughter of Jia Chong and Jia's first wife Li Wan; Li Wan herself was a daughter of Li Feng.

Sima You accompanied his grandfather Sima Yi as he put down Wang Ling's rebellion.³ He also became the heir to his uncle, Sima Shi, who eventually died in March 255 without any sons. It is known that Sima You was a person of mild-mannered character, who was expected to become King of Jin, but ended up being passed over due to his young age.⁴ The heir that was eventually chosen was Sima Zhao's first son, Sima Yan (Emperor Wu), who usurped the Cao Wei throne and established the Jin dynasty with himself as the new emperor in February 266. Sima You was made Prince of Qi on 9 February 266.⁵ Empress Dowager Wang worried about Emperor Wu acting against Sima You; on her deathbed in April 268, while in tears, she told Emperor Wu, "Taofu is rash, while you are not benevolent as an elder brother. After my death, you two are unlikely to tolerate each other. Thus, I entrust him to you. Please don't forget my words."