Nasturtium () is a genus of a small number of plant species in the family Brassicaceae (cabbage family) commonly known as watercress or yellowcress. The best known species are the edible Nasturtium officinale and Nasturtium microphyllum. Nasturtium was previously synonymised with Rorippa, but molecular evidence supports its maintenance as a distinct genus more closely related to Cardamine than to Rorippa sensu stricto.

These plants are related to garden cress and mustard, noteworthy for a peppery, tangy (pungent) flavor. The name Nasturtium comes from the Latin nasus tortus, meaning "twisted nose", in reference to the effect on the nasal passages of eating the plants. Nasturtium foliage is used as food by the caterpillars of certain Lepidoptera, including Orthonama obstipata (The Gem).

One species, Nasturtium gambellii, is federally listed in California as an endangered species.