The text of The Enneads is not a story but rather a discussion of philosophy and a compilation of the ideas of Plotinus, a Greek philosopher from the third century AD. Therefore, there aren't characters per se, as defined by the traditional idea of characters in a story or biography. Instead, Plotinus deals with various ideas. He does, however, use some delineations in his explanations, relating to groups of people. Here are a few of those groups—some of them are not human.

Mankind—those with a soul. His writings here are pertinent in their entirety to humanity, as they are a discussion of his beliefs of the inherent truths that surround humanity at large. He believes that, as humans have reason and intelligence to distinguish between good and evil (and therefore the capacity to truly cause evil), they have souls. This, in Plotinus's mind, is the major delineation between man and beast.

Animals—those without a soul. Plotinus describes the difference between humans and animals as animals being incapable of reason and incapable of distinguishing right from wrong. He does, however, state that this does not prevent them from being intelligent to a degree or incapable of love, but that they are without soul.

Heavens/stars—while these are inanimate objects, Plotinus describes them almost as characters, and they take a very active role in the world. He believes the stars and the heavens are portents of events on Earth, and that they act almost intentionally in their direction of the fates. Plotinus treats them as real beings, to a degree.

The unintelligent man—In his later works, Plotinus describes the nature of intelligence and uses a juxtaposition to analyze what it means. He discusses the idea of a man without intelligence, someone who is irrational and doesn't follow logical pursuits. He reasons that, while they are unintelligent, they still have an innate knowledge of good and evil and therefore are responsible for choosing good, and they have a soul—therefore, they are above beasts in spite of their lack of intelligence.