变色鸢尾（学名：Iris versicolor）是鸢尾科鸢尾属的植物。分布在北美洲以及中国等地，目前已由人工引种栽培。

Iris versicolor is also commonly known as the blue flag, harlequin blueflag, larger blue flag, northern blue flag, and poison flag, plus other variations of these names, and in Britain and Ireland as purple iris.

It is a species of Iris native to North America, in the Eastern United States and Eastern Canada. It is common in sedge meadows, marshes, and along streambanks and shores. The specific epithet versicolor means "variously coloured".