- In Greek mythology, Thalia ("good cheer") was the muse of comedy and pastoral poetry. She was a rural goddess with the attributes of a comic mask and a shepherd's crook. Her names came from θάλλεω, meaning "to bloom".
- The name of one of the Charites
- A nymph, with Zeus or Hephaestus, the mother of the Palici (may be the same as #1 or #2 above)
- An asteroid, 23 Thalia
- a genus of flowering plants, Thalia (plant)
- A popular Mexican actress and musician. See Thalía (actress).