Phaedra is the wife of the Athenian king Theseus and the stepmother of Hippolytus. Left to govern Athens while her husband undertakes a sacrilegious quest in the Underworld, she finds herself overwhelmed by a forbidden, agonizing passion for her stepson. She views her desires as a divine punishment inherited from her mother Pasiphae. She oscillates between a desperate need to preserve her public reputation and a complete surrender to her physical impulses.

Hippolytus is the son of Theseus and an Amazon warrior. He embraces a strict ascetic lifestyle dedicated to hunting and the natural world, venerating the virginal goddess Diana. He harbors a deep, irrational hatred for women and rigidly refuses to participate in traditional civilization. He prefers the purity of the woods to the social expectations of the royal court.

Theseus is the volatile king of Athens. When the narrative begins, he is absent from his kingdom, having descended to the Underworld to help his friend Pirithous abduct the goddess Proserpina. He possesses a cynical, violent disposition. He expects unquestioning obedience from his subjects and acts on intense emotions without stopping to deliberate or gather facts.

The Nurse is an elderly female servant fiercely devoted to Phaedra. She initially serves as a voice of reason, advocating for self-control and virtue ethics. She emphasizes a healthy fear of the gods and retribution. However, her primary drive is a practical loyalty to her mistress, leading her to abandon her moral arguments and formulate deceitful strategies to protect Phaedra's reputation at any cost.

The Messenger is a traditional figure of classical tragedy who arrives to report offstage events to the principal figures. He bears the heavy burden of relaying chaotic developments to the royal family. While his personal background is left unstated, he expresses deep grief over the violent news he must carry to the sovereign.

The Chorus represents a collective voice that observes the unfolding crisis within the royal house. Lacking an independent personal identity, the group functions as a philosophical commentator on the narrative action. They sing of the overwhelming power of love and the unpredictability of fate, viewing human beings as vulnerable subjects to the whims of the gods.