This does contain some spoilers, like who dies, so be prepared! And EVERYONE that had a name, including horses and whatnot, are listed here.

The list for order of appearance has only the characters that had an physical part in the story, not the people that were mentioned only in passing (such as Mirianna Ohmsford - Par and Coll's mother). The one that has the characters organized in alphabetical order has all of them.

Ahren Elessedil: an Elven prince gone Druid, he went with Pen to save the Ard Rhys. He is Khyber's uncle. Ahren was killed when Terek Molt confronted him, but not before he, with the power of the Elfstones to aid him, destroyed both Molt and the Galaphile.
Aphasia Wye: an assassin whose origin is unknown, he is sent by Shadea to kill Pen and his allies. He wields the Stiehl.
Bandit: a moor cat that Pen encountered while trapped in the Slags, it now follows them to Taupo Rough.
Bek Ohmsford: Pen's father; he is in the Wolfsktaag on an expedition and knows nothing about the missing Ard Rhys.
Brona: also known as the Warlock Lord, he is now a shade. Grianne ended up summoning him when she went to the Forbidding's version of the Hadeshorn to ask for help. He told her that a boy was coming to save her and that Shadea a'Ru and the others were nothing but pawns.
Cela Scio: Traunt Rowan's mother, she was a member of the Coalition Council but died because of the Ilse Witch.
Chaser: Grianne's War Shrike; it flew her and Kermadec to Skull Mountain.
Cinnaminson: blind, she is the daughter of Gar Hatch and has magic of her own - she can "see" with her mind and was her father's navigator. She was the only one left alive when Aphasia Wye killed the people of the Skatelow so that she could find Pen for him.
Coran Leah: Quentin's father.
Dannon Scio: Traunt Rowan's father, he was a member of the Coalition Council but died because of the Ilse Witch.
Gar Hatch: a Rover; he was the captain of Skatelow until Aphasia Wye killed him and his crew. He betrayed Pen and Ahren by telling Molt where they were and left them stranded in the Slags.
Gerand Cera: a Druid whose loyalties are unknown.
Grianne Ohmsford: once the Ilse Witch, she is now Ard Rhys. She was trapped inside the Forbidding when Shadea a'Ru used the potion liquid night on her and now must wait for her nephew, Pen Ohmsford, to save her.
Iridia Eleri: an Elven sorceress who loved Ahren Elessedil, she plotted with Shadea a'Ru as well but became controlled by the other thing she was helping - it was the thing from the Forbidding that had given her the liquid night. When it promised to become Ahren for her, it joined with her physically and extinguished her mind.
Kellen Elessedil: son of Kylan and King of the Elves.
Kermadec: a Troll Maturen and head of the Trolls who protected the Ard Rhys, he was sent back to Taupo Rough when all of them were discharged in disgrace.
Khyber Elessedil: daughter of Kylen and brother of Kellen Elessedil, the current Elven King, she goes with Pen to save the Ard Rhys. After the death of Ahren Elessedil, she is entrusted with the Elfstones. She knows some earth magic, which she learned from Ahren.
King of the Silver River: living since the time of Faerie, he appears to Pen Ohmsford to tell him about what he must do to save the Ard Rhys. He also saved him and Tagwen from being seen when the Galaphile sailed above them.
Kylen Elessedil: the late King of the Elves; he was killed on the Prekkendorran when Khyber was a little girl.
Liria Leah: Quentin's mother.
Penderrin Ohmsford: son of Bek and Rue Ohmsford and bearer of a magic that allows him to understand and communicate with everything living, it is he who must find the tanequil, shape the darkwand, and go into the Forbidding alone to save his aunt Grianne.
Pyson Wence: a Gnome that plotted with Shadea.
Quentin Leah: Pen's uncle.
Redden Alt Mer: a Rover captain; he is Pen's uncle.
Rue Meridian: Pen's mother; she is in the Wolfsktaag with Bek and knows nothing about the missing Ard Rhys.
Sen Dunsidan: Prime Minister of the Southland, he received the potion liquid night from Iridia and in turn gave it to Shadea.
Shadea a'Ru: the new Ard Rhys after Grianne vanished, she was the main plotter in trying to get rid of the other. It was she who applied the potion liquid night to Grianne.
Tagwen: Grianne's trusted advisor and secretary. A Dwarf, he goes with Pen to save the Ard Rhys.
Terek Molt: a Druid Dwarf who plotted with Shadea a'Ru, he commanded the airship Galaphile until the use of Ahren's elemental magic and the magic of the Elfstones destroyed both him and the ship.
Traunt Rowan: a Southlander that plotted with Shadea.
Trefen Morys: one of the few Druids who still believe in Grianne.
Weka Dart: an Ulk Bog who speaks an Elven dialect, he was Grianne's guide in the Forbidding until she told him that she wanted to go back to where she first appeared; he left her then. He was banished from his tribe when he ate another's babies.