In the Philip Pullman trilogy "His Dark Materials" the daemon is the embodiment of the soul. Every human is accompanied everywhere by his or her personal daemon.
A child's daemon changes its appearance with the child's mood but an adult's is fixed and reveals his or her true qualities. Thus the Master of Jordan College has the raven, a bird of knowledge.
Visit the web siteof the film The Golden Compass - out now - a link can be found to the right of this article. Follow the Daemon links.
(You have to answer 20 perceptive questions. My daemon turned out to be Thaleron the Tiger.)