堑壕大衣（Trench coat、Trenchcoat）或称战壕大衣、壕沟大衣或风衣，是一种厚实的防水大衣。以棉布、皮革或府绸制成，下摆长度及膝盖至脚踝。最初是第一次世界大战的陆军军官于战壕中所穿的服装，也因此而得名。

A trench coat or trenchcoat is a raincoat made of waterproof heavy-duty cotton gabardine drill, or leather, or poplin. It generally has a removable insulated lining, raglan sleeves, and the classic versions come in various lengths ranging from just above the ankles (the longest) to above the knee (the shortest). It was originally an item of clothing for Army officers (developed prior to the war but adapted for use in the trenches of the First World War, hence its name) and shows this influence in its styling.