Zhèng Dé’ān 鄭德安, hào Chōngxū miàojìng Níngzhēn zǐ 冲虛妙靜寧真子 (“Master Empty-Profound, Marvellous-Quiet, Tranquil-Real”), was a Southern-Sòng Daoist nèidān 內丹 practitioner of the Southern lineage that traced its descent through Zhāng Bóduān 張伯端 (whom Zhèng calls his zǔshī 祖師, “patriarch”). He produced the Jīnyè dàdān kǒujué 金液大丹口訣 (KR5a0292, DZ 280), claiming to have received the formula from a “Daoist clad in white from the Tàiwēi cavern-heaven” (太微洞天白衣道者). The work is internally undated; its quotation of a half-verse from Xuē Dàoguāng’s 薛道光 Huándān fùmìng piān 還丹復命篇 places it no earlier than the late twelfth century. Beyond the work itself, no biographical record survives.