The speaker of the poem is a poet wandering through the Somerset environs near Alfoxden. He actively disputes the traditional literary notion that the nightingale's song is melancholy, viewing it instead as an expression of nature's joy. He advocates for surrendering one's spirit to the natural world rather than relying on inherited poetic tropes about sorrow.

A fellow poet and close companion who shares the speaker's philosophical views regarding the natural world. He acts as a silent but supportive auditor during the evening excursion. He agrees that the environment is fundamentally an expression of love and joy, rejecting any projection of human sadness onto the surrounding woods.

Affectionately addressed as "our Sister" by the speaker, she acts as a silent but vital presence during the nighttime stroll. She shares the men's deep appreciation for the joy found in the surrounding environment. Her quiet attentiveness during the walk mirrors the receptive attitude the speaker advocates for all nature lovers.

The birds inhabiting the wild, tangled grove near an empty castle. They fill the air with sweet, harmonious, and joyful songs, interacting with each other through swift murmurs and low piping sounds. Rather than mournful creatures, they actively express the beauty and merry energy of the nighttime forest.

The speaker's young son, described affectionately as a "dear babe." Though unable to speak, he exhibits an innate wisdom and a natural affinity for the nighttime sky. He recognizes the evening star and finds immediate comfort in the sight of the moon when waking from distressing dreams.

A young woman who regularly glides through the pathways of the local woodland. She possesses an almost religious devotion to the outdoors, resembling a nun dedicated to the forest. She knows every note of the birds' songs and carefully observes their reactions to the shifting moonlight.

A figure from classical mythology whose story is traditionally linked to the mournful interpretation of the bird's song. In the referenced myth, she suffers severe violence and transforms into a bird to escape her tormentor. The speaker actively argues against using her "pity-pleading" story to interpret the actual sounds of the forest.

A mythological king whose violent actions toward his sister-in-law precipitate a famous tragedy. His extreme cruelty causes the frantic flight and eventual transformation of the sisters. His presence in the text serves entirely as background for the tragic literary trope the speaker rejects.

The sister of Philomela and wife of King Tereus in classical Roman mythology. She flees with her sister to escape her husband's vengeful anger following his brutal actions.