Guo Jun (??; Pinyin: Guojùn) (born 1974) is a Buddhist monk in Singapore, and one of the youngest Dharma heirs of Chan Master Sheng-yen.
His complete Dharma name is Zhengyan Guojun (????).
He has published three books: Essential Chan Buddhism,Chan Heart, Chan Mind and Falling is Flying: The Dharma of Facing Adversity together with Ajahn Brahm.