Zhèng Ruòzēng 鄭若曾 (1505–1580), zì Bólǔ 伯魯, hào Kāiyáng 開陽, was a Late-Míng coastal-defence and frontier-strategy specialist. Native of Kūnshān 崑山 (Sūzhōu region). Personally close to Hú Zōngxiàn 胡宗憲 (Mid-Míng wōkòu suppression chief) and Qī Jìguāng. Major works in the SKQS: Jiāngnán jīng lüè 江南經畧 (KR3b0018, his comprehensive treatment of Lower-Yangzi defence in 8 juan); Chóu hǎi tú biān 籌海圖編 (separately preserved, the major coastal-defence atlas).