Péng Xiǎo 彭曉 (d. 955), zì Xiù chuān 秀川, hào Zhēn yī zǐ 真一子, was a Five-Dynasties Daoist alchemist who served under the Latter Shǔ 後蜀 (Sìchuān). His Zhōu yì cān tóng qì fēn zhāng tōng zhēn yì 周易參同契分章通真義 (KR5d0019), with accompanying Dǐng qì gē míng jìng tú 鼎器歌明鏡圖 (KR5d0020), is the single most influential traditional commentary on the Cān tóng qì — dated by its colophon to 947. Péng’s division of the text into three juàn and his reading of the work as a systematic inner-alchemical (nèi dān) treatise shaped the subsequent Sòng and later tradition of Cān tóng qì studies, including Zhū Xī’s own work.