Tethys or Tethis may refer to: Tethys (database), an online knowledge management system about the environmental effects of offshore renewable energy Tethys (gastropod), genus of gastropods in the family Tethydidae Tethys (moon), a natural satellite of Saturn Tethys (mythology), a Titaness in Greek mythology Thetys (salp), a genus of gelatinous sea salp Tethys Ocean, a Mesozoic-era ocean between the continents of Gondwana and Laurasia Tethys Research Institute, a non-governmental scientific organisation based in Italy "Tethys", a song from The Ocean of the Sky by The Used Tethys, the Japanese name for "Thetis", a boss character in Mega Man ZX Advent Tethys River, an interplanetary waterway in Dan Simmons's Hyperion Cantos See also Thetis (disambiguation)