Gao Yun (died 409), at one time Murong Yun, courtesy name Ziyu, formally Emperor Huiyi of (Later)/(Northern) Yan, is an emperor who, depending on the historian's characterization, is either the last emperor of the Chinese/Xianbei state Later Yan, or the first emperor of its succeeding state Northern Yan.

He is ethnically Korean and a descendant of the royal house of Goguryeo, whose ancestors were captured by Former Yan.

He is adopted into the Later Yan imperial house after helping the emperor Murong Bao (Emperor Huimin) put down a rebellion by Murong Bao's son Murong Hui.

He becomes emperor after the people rebel against the despotic rule of his adoptive uncle Murong Xi (Emperor Zhaowen), and during his reign, he uses the title "Heavenly Prince" (Tian Wang).

In 409, he is assassinated, and after a disturbance, is replaced by his ethnic Han Chinese general Feng Ba (Emperor Wencheng).