Chǔ zé xiān sheng 楚澤先生 (“Master of the Chǔ Marshes”) was the pseudonymous Táng Daoist compiler of KR5c0279 Tài qīng shí bì jì 太清石壁記 — an alchemical compendium compiled 758 or 759. The pen-name suggests a recluse of the lower Yángzǐ / former Chǔ 楚 region; his real name is unrecorded.