Familiars

From Dictionary.com:

fa·mil·iar[fuh-mil-yer]
–noun
1.a familiar friend or associate.
2.an animal, as a cat, that embodies a supernatural spirit and aids a witch in performing magic.
3.familiar spirit.

From Wicca.com

Familiar:
An animal that has a spiritual bone with a witch; many times a family witch. Familiars can also be entities that dwell on the astral plane.

According to my Ecclasian teachings, a familiar may be of 3 different kinds.  A Human spirit of a dead person, a non-human spirit or elemental, or an actual physical creature such as a small animal (i.e. cat, dog, mouse, etc.).  Most often people will think of a familiar as a cat, generally depicted as a black cat for a witch.  However with recent years, and the phenomonon of Harry Potter, more “exotic” animals have been linked with Familiars (such as the white Owl or the rat).

Human Spirit Familiars:

These are commonly thought of as “Spirit Guides”.  Often attaching themselves to a channel or medium to aid them in communicating with deity or communicating more clearly with the dead.  Sometimes these spirits are close family members who have passed on but still watch over their family and guide them when they feel they are needed.  My own personal grandmother has popped up in my life and other family members lives at key moments.

Non-Human Spirit – Elementals:

These non-human spirits are sometimes also known as Nature Spirits.  Often these spirits will dwell within particular objects such as gems, crystals, mirrors, etc.

Material Creature Familiars:

This is the most commonly know and frequently found type of familiar.  This type of familiar has many “uses”.  They can divine, ground negative energy, exude vitality, help with astral travel, guard against unfriendly “visitors” and are often attracted to circles or where ever there is energy work being done.