Spirits were beings that were not fixed to a particular form or body.
The following list of the world of Narnia Spirits: -
Dryad[]
Dyrads, or Tree Nymphs, are capable of leaving their trees and assuming a physical body almost identical to human form. If a tree is cut down, the Dryads will die and enter Aslan's Country.
Hamadryad[]
Wood spirits were similar to Dryads, but use their own trees to assume a body resmbling a human form, Lewis describes a birch hamadryad as having "a soft, showery voice and would look like a slender girl, with hair blown all about her face, and fond of dancing" and an oak hamadryad as looking like "a wizened, but hearty old man with a frizzled beard and warts on his face and hands, and hair growing out of the warts". A whole swarm of hamadryads dance sleepily around Lucy and Aslan when they are reunited in Prince Caspian.
Horror[]
Evil creatures present at the sacrifice of Aslan. Horrors have the body of a human, face of a gazelle and scales of a reptile.
Naiad[]
Spirits of the rivers, lakes, wells and streams. They were led by their father and leader, known simply known as "The River God", who is described by Lewis as having a "great wet, bearded head, larger than a man's, crowned with rushes.",though the term "river god" is usually titled to male naiads in general. When a stone bridge was built over a river, the Naiads in it were imprisoned in the river. They were capable of marrying human men and women, and able to sire human children.
Nymph[]
Spirits that lived in the trees and waters. They were capable of leaving their tree or watery domains, and assuming a physical body resembling human form. This term is usually used for female Dryads, Hamadryads, and Naiads.
River God[]
Water spirits of the same species as the Naiads, but male in form. River gods, as their name goes, only inhabit rivers, while water nymphs inhabit rivers.
Tree People[]
Tree People are Wood gods and goddesses who use their trees as their physical bodies. Lewis doesn't specify whether they are the same as dryads or just a different sort of wood spirit, but they are described as beautiful giants and giantesses who have branch-like hair and fingers. They have roots for feet, and wade in the earth like humans do in water.
Spectre[]
Spectres are malevolent ghosts that followed Jadis in her army
Wraith[]
Dark ghostly spirits that aided Jadis in her conquest.