Sima Ai or Sima Yi (司馬乂)[3] (277 – 19/20 March 304[4]), courtesy name Shidu (士度), formally Prince Li of Changsha (長沙厲王), was a Jin dynasty imperial prince who briefly served as regent for his half-brother Emperor Hui.
Of the eight princes, he alone received praises from historians, for his attempt to reform government and his courtesy to Emperor Hui, who was developmentally disabled.
[5] According to the Book of Jin, Sima Ai was a strong and resolute man and was seven chi and five cun tall (approximately 1.84 metres).
He became arrogant and extremely controlling, and failed to pay even basic courtesies to Emperor Hui.
(Before he was executed, Sima Ai was able to write a touching letter of farewell to Emperor Hui.)