Personality types

Sanguine? Choleric? Melancholic? Phlegmatic? Introvert?  Extrovert?  Intuitive?  Sensing?  Thinking? Judging? Feeling?  Perceiving? Lion? Otter?  Golden Retriever?  Beaver?

There are so many personality types, so many different ways of "classifying" ourselves and other people.  I've been wondering about this a lot lately.  The question is, do we ever change or are we "stuck" with our personality types?  Any thoughts?