Yes it appears in the form of the wise old man or woman an archetype of wisdom. Usually this archetype gives the hero some sort of magical item or some kind of instrument. Campbell said he also gives him a psychological commitment. In movies characters like obi wan kenobi or Gandalf seem to be a representation of the Self although if you ask me, a shallow one, they still do the trick.
Jung thought of it as the God within us. Hope this helps.