Huán yáng zǐ 還陽子 (“Master Return-Yáng”) was a late-Táng or Five-Dynasties Daoist alchemist, author of KR5c0337 Dà huán dān jīn hǔ bái lóng lùn 大還丹金虎白龍論 (“Discourse on the Gold-Tiger and White-Dragon of the Great Return-Elixir”). The name is a pseudonym.