Apsara is Hindu water and cloud spirit, sometimes represented as mermaids.
They are actually shapechangers. Since Apsaras are related to water, they can be compared to Greek Nymphs, Dryads and Naiad. They also care for fallen heroes, like Valkyries of North.
Apsaras like to dance a lot, they are said to live in Indra (heaven) and come down to seduce men with their dance. Thus they are mostly represented by dancing figures in art and architecture.
- Paul Carus, THE HISTORY OF THE DEVIL