A flying buttress is a masonry element which leans or arches over a gap to support a larger wall or framework. In contrast to a normal buttress, a flying buttress is not attached to the supported element along its full height, but only toward the top, thus forming an opening.

Flying buttresses are a flamboyant design element, opening up the framework of a structure and increasing its visual complexity. They are a hallmark of gothic architecture, and are used most frequently in cathedrals and large churches.

Faux flying buttresses, which are generally decorative and do not provide any significant structural support to anything else, may also be listed as flying buttresses, as their contribution to a building's design is similar. These may be constructed with a metal, concrete, or wood core clad in a masonry veneer.