Eleocharis palustris, the common spike-rush, creeping spike-rush or marsh spike-rush, is a species of mat-forming perennial flowering plants in the sedge family Cyperaceae. It grows in wetlands in Europe, North Africa, northern and central Asia (Siberia, China, Mongolia, Iran, Nepal, etc.) and North America (United States, Canada, Greenland, northern Mexico). Eleocharis palustris is not easily distinguished from other closely related species and is extremely variable worldwide itself. The species epithet palustris is Latin for "of the marsh" and indicates its common habitat.
Numerous names have been proposed for subspecies and varieties. The following are recognized: