Taran is an orphaned farmhand in his early teens living at the Caer Dallben stronghold. He holds the title of Assistant Pig-Keeper, a role he feels falls far below his ambitions for glory. He is restless, impatient, and eager to leave home to prove his bravery, though he lacks training in survival or combat.

Eilonwy is a twelve-year-old descendant of the Sea People, residing in the Spiral Castle under the instruction of Queen Achren. She studies enchantment and possesses a magical glowing ball she calls her "bauble." Highly intelligent and talkative, she sharply objects to being treated as helpless or subordinate.

Prince Gwydion is a hero of Prydain and heir apparent to the House of Don. He travels undercover wearing coarse, travel-stained clothing and sporting shaggy, gray-streaked hair. He actively tracks the forces of Annuvin to protect the land from an impending attack.

The Horned King is a massive warlord acting as a champion for the forces of Annuvin. He wears a blood-red cloak and a helmet constructed from a human skull topped with large antlers. He commands a violent band of mercenaries and scours the countryside searching for the oracular pig, Hen Wen.

King Arawn is the dark king of Annuvin, the Land of the Dead. He seeks to conquer the entirety of Prydain and subjugate its people. He commands an army that includes the terrifying Cauldron-Born, undead warriors immune to normal weapons, and giant, fierce birds known as gwythaints that act as his spies.

Queen Achren is a beautiful but deeply wicked ruler residing in the Spiral Castle. She commands loyalty from the undead Cauldron-Born and possesses powerful, destructive magic. She seeks to manipulate the conflict between Prydain and Annuvin for her own gain.

Gurgi is a furry, half-man and half-animal creature who lives in the forests of Prydain. Shunning both human and animal societies, he survives by scavenging and begging travelers for "crunchings and munchings." His awkward attempts to please others mask a deep desire for acceptance.

Fflewddur Fflam is a traveling bard who wanders Prydain carrying a beautiful harp given to him by the Chief Bard Taliesin. He wears ragged clothing but insists he is a king taking a break from a vast territory. Whenever he exaggerates his past exploits, a string on his harp snaps.

Doli is a stout, heavily armed warrior of the Fair Folk. Unlike the rest of his family, he cannot turn invisible by holding his breath, a limitation that leaves him with the bulk of the community's chores. This makes him exceptionally grumpy, though he is highly skilled at gem-cutting and finding his way through underground passages.

Dallben is a 379-year-old wizard who rules over the agricultural stronghold of Caer Dallben. He is tall and heavily bearded, spending much of his time reading from a mysterious tome called The Book of Three or napping in his crowded study. He oversees Taran's education while shielding him from the dangers of the outside world.

Hen Wen is an oracular pig living at Caer Dallben. She possesses the ability to make prophecies, information that is deciphered using special letter sticks. Having once been a prisoner of Annuvin, she is highly sensitive to danger and flees into the forest when she senses the approach of evil forces.

Melyngar is Gwydion's white mare, distinguished by her golden mane. She possesses high intelligence and understands the terrain of Prydain intimately, able to find safe passes and paths when human riders are lost. She is an active participant in skirmishes, using her hooves to fend off attackers.

Medwyn is an ancient protector of animals who lives in a hidden alpine valley in the Eagle Mountains. He is powerfully built, with white hair down to his shoulders and a gold band around his forehead. He provides a safe sanctuary for creatures fleeing the violence of the outside world, strictly limiting human access.

Eiddileg is the king of the Tylwyth Teg, the Fair Folk who live in a massive society beneath the Black Lake. He is a short, bearded monarch prone to dramatic fits of rage and frustration over the constant demands humans place on his people. Despite his explosive temper, he governs a thriving and harmonious civilization.

Coll is an elderly, stout, bald-headed man residing at Caer Dallben. He teaches Taran practical skills like farming and metalwork. He is patient and good-humored, even when playfully parrying Taran's attempts at learning swordplay with a fire poker.