Carl Jung did some very good analysis on many of the psychological archetypes and in what ways could they affect us. This is a very interesting concept of his.

The Shadow Archetype according to Jung is a personification of all those aspects of ourselves that aren't part of the personality. The collective unconscious can be considered part of it. So not only those it carry our destructive impulses, but also the creative parts are part of it. Jung believed that facing those archetypes can be painful, but it is neccesary to develop a more healthy personality.