Yunyan Tansheng (Chinese: 雲巖曇晟; pinyin: Yúnyán Tánshèng; Wade–Giles: Yün-yen T'an-shêng; Japanese: Ungan Donjō; Korean: Unam Tamsŭng; Vietnamese: Vân Nham Đàm Thạnh) was a Chán Buddhist monk during the Tang dynasty.

[1][2] The first part of his name comes from Yunyan Mountain, which is outside of modern Changsha, where he taught after studying with Yaoshan.

Recorded dialogues involving Yunyan often include him and his fellow student, Daowu Yuanzhi.

[1] A well known poem, the Song of the Precious Mirror Samādhi, is attributed to Yunyan in Juefan Huihong's biographical compilation of 1119, the Chanlin sengbao zhuan (Chronicle of the Saṅgha Treasure in the Groves of Chán).

[3] A number of kōan dialogues feature Yunyan and his fellow student Daowu Yuanzhi.