Huángbò Xīyùn (simplified Chinese: 黄檗希运; traditional Chinese: 黄檗希運; Wade–Giles: Huang-po Hsi-yün; literally "Xiyun of Mt. Huangbo", Japanese: Ōbaku Kiun) (died 850) was an influential Chinese master of Zen Buddhism during the Tang Dynasty.

Huángbò was a disciple of Baizhang Huaihai (720-840), and the teacher of Linji Yixuan (died 866) (Wade-Giles: Lin-chi I-hsüan; Japanese: Rinzai Gigen).

Very little about Huángbò‘s life is known for certain as, unlike other Transmission of the Lamp literature, there is no biographical information included with Huángbò‘s collection of sayings and sermons, the Ch’uan-hsin Fa-yao (Essential of Mind Transmission) and the Wan-ling Lu (Record of Wan-ling: Japanese: Enryōroku).

He was born in Fujian, China. The records indicated that Huángbò was extraordinarily tall.

Huángbò began his monastic life on Mt. Huangbo in Fuzhou (Fu-chien) province, receiving the Buddhist name Hsi-yun. As was the custom of the times, he traveled around seeking instructions from various Chan masters. He visited Mt. Tiantai and sought teachings from the National Teacher Nanyang Huizhong (Wade-Giles: Nan-yang Hui-chung; Japanese: Nan’yō Echū). At some point he may also have studied under Nanquan Puyuan (748-835) (Wade-Giles: Nan-ch’üan P’u-yüan; Japanese: Nansen Fugan), a student of Mazu Daoyi (Wade-Giles: Ma-tsu Tao-i; Japanese: Baso Dōitsu) (709-788)