It's hard to describe what a nymph actually is. The line between god and human is blurred when it comes to nymphs. Some were simply women, nothing more, and others had the powers of an immortal. Nymphs were often taken by the gods as lovers, and there are a lot of cool stories.

Dryads and Hamadryads

Dryads and Hamadryads are tree nymphs, whose lives end when their tree dies. They often accompanied Apollo, Hermes, Pan, and the Satyrs.

Meliae

The Meliae were ash-tree nymphs who were similar to the Hamadryads. They were born from the blood of Uranus' severed genitals.

Nerieds

The Nerieds are mermaids whose parents are Nereus, often called the Old Man of the Sea, and the nymph, Doris. There were 50 sisters, and one of them was Thetis, the mother of Achilles.

Oceanids

Oceanids were the daughters of Ocean and Tethys, and were the nymphs of that "great river."

Naiads

The Naiads were water nymphs and the daughters of Zeus. They dwelt in brooks, springs, and fountains - wherever there was running water. The Naiads helped those with intentions to their liking and relatives.

Oreads

Nymphs of the mountains and hills.

Stygian Nymphs

The Stygian Nymphs were the ones Perseus sought out for magic tools to help with his task of beheading Medusa. From them he obtained a magic wallet that we could carry Medusa's head in, a pair of winged sandals, and Hades' helmet of invisibility.

Hesperides

These three nymphs, whose names are Hespere, Aegle, and Erytheis, were the daughters of Atlas and Hesperis. They guarded the golden apple tree that Gaia gave Hera as a wedding present, but were replaced by the dragon, Ladon, when Hera realized they had been stealing the apples.

Hyades

The Hyades were originally called the Nysaean nymphs. Zeus placed Dionysus in their care as an infant. As gratitude, Zeus placed them among the stars calling them the Hyades.

Pleiades