Agrostis gigantea, known by its common names black bent and redtop, is a perennial grass of the Agrostis genus.
It is native to Europe, but in the cooler areas of North America was widely used as a pasture grass until the 1940s. Although it has largely been replaced by soybeans and more palatable grasses, it still gets some use in poor soils. It was one of the grasses planted in areas disturbed by the Trans-Alaska Pipeline. It generally does well in response to fires, due to survival of rhizomes and seeds. It can be found in open woodland, rough grassland, hedgerows, roadsides and waste ground, and as a weed on arable land.