Green Leaves, originally known as Koontz House, is a Greek Revival mansion in Natchez, Mississippi, completed and then much extended during the early- to mid-1800s. It was listed on the National Register of Historic Places (NRHP) in 1979. The listing documentation notes that although it is "a somewhat static setting" externally, "the interior design of the house is notable for both its excellence and integrity". It includes not merely many period architectural features but also period decoration and contents, which together make it "one of the most valuable national documents of mid-nineteenth century taste". It is one of several historic buildings in Natchez which adopted the Greek Revival style and which maintain significant historic interiors.