Irene is a young, curious princess being raised in a large house in the mountains, safely away from the kingdom's capital. She possesses eyes that resemble the night sky and maintains a brave disposition despite her youth. Sheltered by her caretakers due to the threat of subterranean goblins, she longs to explore her surroundings. Her natural kindness dictates how she treats everyone she meets, regardless of their social standing.

Curdie is a twelve-year-old miner boy who works alongside his father in the mountain caverns. He is cheerful and quick-witted, remaining entirely unbothered by the goblins since he knows his improvised singing keeps them at a distance. As a working-class youth, he relies on practical knowledge of the mountains and the underground tunnels. He acts bravely to protect those he encounters in the dark.

Grandmother, also named Irene, is a mysterious, youthful-looking elderly woman who lives secretly in the highest tower of the farmhouse. She spends her days spinning a remarkably fine thread from spiderwebs gathered by her flock of pigeons. She acts as a comforting and wise presence for the young princess when she feels afraid. Most of the household remains completely unaware of her existence.

The King-Papa is the ruler of the land and Irene's affectionate father. His royal duties keep him traveling across the country, limiting the time he can spend at the mountain farmhouse. He exhibits gentle authority and cares deeply for his daughter's well-being. He rules with a strict focus on safety and protecting his subjects from external threats.

The Goblin King rules the subterranean race that lives beneath the mountain. He harbors deep resentment toward the humans living above ground, viewing them as invaders of the goblins' ancestral lands. Despite his authority, he generally defers to his more aggressive wife in matters of strategy and revenge.

The Goblin Queen is the aggressive and domineering wife of the Goblin King. She insists on wearing heavy granite shoes to hide physical traits that link her to surface-dwelling humans. She is ruthless and vocal in her desire to exact revenge on the people of the mountain.

Prince Harelip is the immediate heir to the goblin throne. He shares his stepmother's cruel disposition and plots to force a human princess into marriage against her will. His ambitions pose a direct threat to the safety of the surface dwellers and the human royal family.

Lootie serves as the primary nursemaid and caretaker for Princess Irene at the mountain farmhouse. She is fiercely devoted to the princess but is highly prone to panic, particularly regarding the dangers of the mountain after dark. She possesses a rigid view of social class and deeply mistrusts the local working-class miners.

Curdie's Mother is a hardworking woman who provides a warm, comforting home for her husband and son. She possesses an open mind regarding the mysteries of the world and remembers local lore from her youth. Her gentle logic helps guide her son when he struggles to understand experiences that fall outside his practical worldview.

Curdie's Father, sometimes referred to as Peter, is a seasoned miner who works deep within the rock face. He relies on practical knowledge to move safely through the dangers of the underground tunnels while providing for his family. He implicitly trusts his son's judgment and capabilities in the mines.

Glump is a common goblin who lives in the caverns close to the human mines. He attends the king's court and participates actively in the goblins' underground society. His casual conversations unintentionally reveal critical information to those listening on the other side of the rock.

Helfer is a young goblin child who works alongside his father in the underground passages. Like all goblins, he has highly sensitive feet without toes, which makes him vulnerable to injury.