The Enneagram is great.

Jungian Archetypes.

As a screenwriter/psychologist, I've made use of Jungian Archetypes. This divides up various parts of the character's conscience into its heart (emotional connection), ego(intellectual), soul (the moral compass, or the superego), and the shadow (the characters dark side). Each of these is reflected in the characters supporting cast. For example, in Star Wars, Luke can be broken down this way. Obi-Wan Kenobi as the soul; Leia as the heart; Han Solo as the ego; and Darth Vader as the shadow.

There is an excellent book called Psychology for Screenwriters. Therein contains excellent psychology-based screenwriting theory.