Ostara may refer to:
- the Old High German for "Easter", cognate to Anglo-Saxon Ēostre
- Spring Equinox (Ostara), the Neopagan and Wiccan festival celebrated around spring equinox
- The asteroid 343 Ostara
- The American Artemis class attack cargo ship USS Ostara (1944–1946), named after the asteroid
- Ostara (magazine), a 20th-century occult publication of Lanz von Liebenfels
- Ostara (band), a neo-folk musical group
- Ostara (album), an album by The Wishing Tree
- Ostara Publishing, a British publisher
- Ostara Nutrient Recovery Technologies Inc., a Canadian company specializing in resource recovery from wastewater and sewage sludge treatment