卧虎藏龙 (Wò hǔ cáng lóng)

Literally: Crouching tiger hidden dragon

Example: “这个小镇卧虎藏龙，菜市场的大爷原来是书法家。” — This little town is full of dark horses: the old man at the market turned out to be a calligrapher.

English equivalent: Dark horse

Origin: Traces to a specific literary couplet by Yu Xin, a major 6th-century poet of the Northern and Southern Dynasties period, from his poem written during a visit with a fellow official at Heyang: "暗石疑藏虎，盘根似卧龙" — a dark, shadowed rock seeming to conceal a hidden tiger, gnarled tree roots coiling like a crouching dragon. Yu Xin's original lines were a purely descriptive flourish about a striking, dramatic landscape, with no hidden meaning about people at all. Later use of the phrase repurposed his vivid natural imagery into a figurative statement about people instead: a place, group, or organization that looks unremarkable on the surface but actually conceals impressive, still-unrecognized talent — talent as easy to overlook, until you know to look for it, as a tiger crouched in shadow or a dragon coiled invisibly among tangled roots.