Legendary disciple of Lǎozǐ 老子, known only from Zhuāngzǐ 莊子 ch. 23 (Gēngsāng Chǔ 庚桑楚, in the Zá piān 雜篇), which presents him as a man of Chén 陳 who had “uniquely obtained the Way of Lǎozǐ” (偏得老子之道) and who withdrew to Mt Wèilěi 畏壘山 with a household of maids of unaffected speech and servants of unaffected manner. After three years of wúwéi 無為 governance the region enjoyed a miraculous harvest; when the awed locals proposed to sacrifice to him as a spirit, Gēngsāng refused, saying that the sage rules invisibly “inside a chamber four paces square.” The chapter recounts his dispatch of the youth Nán Róng Chū 南榮趎 to Lǎozǐ for further instruction.
A later Daoist hagiographic tradition — preserved in the prefatory notice of DZ 669 Dòng líng zhēn jīng (KR5c0050) — relocates Gēngsāng’s retreat to Mt Yǔshān 羽山 and then to Mt Yú fēng 盂峯 at Pí líng 毗陵 (Cháng zhōu), where he “completed the Way and ascended as an immortal.” The same notice lists him among the immortals enshrined at the Zhāng Gōng Tán 張公壇 — also known as the Dòng líng Guān 洞靈觀 — reconstituted as the Tiān shēn Wàn shòu Gōng 天申萬壽宫 in the Northern Sòng.
In 742 Táng Xuánzōng 唐玄宗 enfeoffed Gēngsāng Chǔ posthumously as Dòng líng zhēn rén 洞靈真人 (“Perfected of the Communion with the Divine”), on the pattern of the parallel canonisations of Zhuāngzǐ 莊子 as Nánhuá zhēn rén 南華真人, Lièzǐ 列禦寇 (列禦寇) as Chōngxū zhēn rén 沖虛真人, and Wénzǐ 文子 as Tōngxuán zhēn rén 通玄真人. The hermit Wáng Shìyuán 王士源 (fl. 742) was accordingly commissioned to compose a scripture in Gēngsāng’s name; the resulting nine-piān Kàngcāng zǐ 亢倉子 was then promulgated under the canonical title Dòng líng zhēn jīng (KR5c0050). Gēngsāng is thus in the received Daoist tradition regarded as one of the “four disciples of Lǎozǐ” alongside Zhuāngzǐ, Lièzǐ, and Wénzǐ — though his historicity is unattested outside the Zhuāngzǐ parable.
The alternative personal name Kàngcāng zǐ 亢倉子 (also written 亢桑子) appears already in the Hàn-period bibliographic imagination and is used interchangeably with Gēngsāng zǐ in the pre-742 and post-742 literature. Both names appear in the body of DZ 669 itself, with 亢倉子 being the more frequent form in the scripture’s narrative. Under the traditional attribution Gēngsāng is dated to the late Warring-States period (roughly contemporary with Lǎozǐ and Zhuāngzǐ); no independent biographical tradition exists. Modern scholarship (Schipper & Verellen 2004, 1:302–03, U.-A. Cedzich) treats Gēngsāng Chǔ as a purely literary figure of Zhuāngzǐ ch. 23, with the Dòng líng zhēn jīng being an eighth-century Daoist pseudepigraphon composed in his name.
Gēngsāng’s reputed birthplace in Chén 陳 (roughly modern eastern Hénán) reflects the Zhuāngzǐ chapter’s opening line; no CBDB record exists for him.