Lamia: She is a serpent with a woman's head who is given the body of a woman. She has no family, but she has seen and fallen in love with Lycius. Once she is fully turned into a woman, she and Lycius live in an invisible enchanted palace until he wants to go public with their love and marry. After they do, she is denounced by Lycius's former tutor. She is sometimes seen as representing poetry.

Lycius: He is the young Corinthian philosopher who Lamia loves. They live together but he is restless, wants to make their "sweet sin" legitimate through marriage, and persuades Lamia they should marry publicly. He is in love with Lamia and dies of grief when she disappears. He is sometimes seen as representing the dreamer.

Apollonius: He is Lycius's tutor. He is able to see through the illusions Lamia has wrought. He shows up uninvited at the wedding feast and insists over and over that she is "a serpent!" He is dismissive and unkind towards Lamia and has the ability to terrify her. He is sometimes seen as representing reality or reason, which can destroy the illusions woven by poetry.

Hermes: Hermes, the son of Zeus, messenger of the Gods, and muse of poetry meets Lamia, at this point a serpent, in the forest as he pursues a nymph who Lamia has made invisible. She strikes a bargain with Hermes and agrees to make the nymph visible if he will bring back her human form. He does, setting the plot in motion.