The Poet is a sensitive, highly educated young man driven by an intense hunger for truth and ideal beauty. He abandons his familiar life to travel through wild terrains and remote ancient ruins, seeking a pure communion with nature. His pursuit makes him increasingly detached from conventional society, causing him to reject accessible human affection in favor of his abstract, solitary ideals.

Alastor is the titular "Spirit of Solitude" and a terrifying mythological presence drawn from ancient lore. Acting as an unseen driver, this shadowy force tempts the conflicted Poet to abandon human interactions entirely. It operates as a relentless energy that pulls the young wanderer deeper into his own subjective imagination and away from the comforts of the tangible earth.

The Narrator is a reflective, reverent speaker who shares his lifelong devotion to the natural world. He observes the seasons, animals, and natural elements with gratitude, finding peace in his connection to them. Unlike the subject of his tale, he respects the boundaries of nature and remains content without attempting to force his way into its deepest, hidden sanctuaries.

The Arab Maiden is a young woman who encounters the Poet during his travels through the wilderness. She becomes deeply enamored with him, quietly spreading his matting and watching over him while he sleeps. Her gentle, earthly affection goes entirely unnoticed by the Poet, representing the human warmth and community he leaves behind.

The Veiled Maid is a radiant, ethereal figure who speaks in a voice resembling the sounds of streams and breezes. In the Poet's dream, she discusses knowledge, truth, virtue, and divine liberty before embracing him. Her appearance acts as a powerful catalyst, inciting the Poet's relentless desire to find her equivalent in the waking world.