A scupper, in architectural terms, is not some name for a lowly pirate, but rather a device to get water off a roof and away from a building. Most typically found on flat roof buildings, scuppers project out from the sidewall of a building at roof level and allow rainwater and snow melt to flow not just off the roof, but hopefully also away from the edge of the building. In the image above, that standard shape is called a lamb's tongue.
This is a photo of a scupper we designed a few years ago with a rain chain attached. In Colorado, our snow melt creates a slow dripping of water that repeated plunks in gutters and downspouts. A combination of scupper and downspout allows the flow of the water down to a drain without the monotonous aural torture of the equivalent of the late-night dripping sink.
Gargoyles are imaginative, decorative versions of scuppers, most commonly found on Gothic buildings with water spitting ruefully from their fang-filled mouths.