Althaea is the Latin rendering of Greek Ἀλθαία Althaia, which may be related to Greek ἀλθος althos "healing". It can refer to:
- Althaea (mythology), the daughter of Thestius and mother of Meleager
- Althaea (genus), a genus of up to a dozen species of perennial herbs, native to Europe and western Asia, that includes the marshmallow plant
- 119 Althaea, an asteroid
- Althaea is also the name of several nymphs in Greek mythology
- "Shrub Althea", "Shrub Althaea" and "Rose of Althea" are names applied to Hibiscus syriacus, which is South Korea's national flower
Althea, an English variation of the Greek name, can refer to:
- Althea, a female first name
- USS Althea, any of three U.S. Navy ships
- EUFOR Althea, a European Union military operation
- "Althea", a Grateful Dead song
- Althea, a fictional pulsar from the science-fiction novel The Hercules Text by Jack McDevitt
- Althea, an English frigate in the Napoleanic wars.
Altea, a Spanish variation of the Greek name, can refer to:
- Altea, a town in Spain