The Fantasy Review‘s list of 8 Fantastic Fantasy Book Quartets.
Millennium’s Rule by Trudi Canavan
From the blurb of book 1:
In a world where an industrial revolution is powered by magic, Tyen, a student of archaeology, unearths a sentient book called Vella. Once a young sorcerer-bookbinder, Vella was transformed into a useful tool by one of the greatest sorcerers of history. Since then she has been collecting information, including a vital clue to the disaster Tyen’s world faces.
Elsewhere, in an land ruled by the priests, Rielle the dyer’s daughter has been taught that to use magic is to steal from the Angels. Yet she knows she has a talent for it, and that there is a corrupter in the city willing to teach her how to use it — should she dare to risk the Angels’ wrath….
The Long Price Quartet by Daniel Abraham
From the blurb of book 1:
The powerful city-state of Saraykeht is a bastion of peace and culture, a major center of commerce and trade. Its economy depends on the power of the captive spirit, Seedless, an andat bound to the poet-sorcerer Heshai for life. Enter the Galts, a juggernaut of an empire committed to laying waste to all lands with their ferocious army. Saraykeht, though, has always been too strong for the Galts to attack, but now they see an opportunity.…
The Faithful and the Fallen by John Gwynne
From the blurb of book 1:
The world is broken. . .and it can never be made whole again.
Corban wants nothing more than to be a warrior under King Brenin’s rule — to protect and serve. But that day will come all too soon. And the price he pays will be in blood.
Evnis has sacrificed — too much it seems. But what he wants — the power to rule — will soon be in his grasp. And nothing will stop him once he has started on his path.…
The Inheritance Cycle by Christopher Paolini
From the blurb of book 1:
When fifteen-year-old Eragon finds a polished blue stone in the forest, he thinks it is the lucky discovery of a poor farm boy. But when the stone brings a dragon hatchling, Eragon soon realizes he has stumbled upon a legacy nearly as old as the Empire itself.
Overnight his simple life is shattered, and, gifted with only an ancient sword, a loyal dragon, and sage advice from an old storyteller, Eragon is soon swept into a dangerous tapestry of magic, glory, and power. Now his choices could save—or destroy—the Empire….
The Raven Cycle Series by Maggie Stiefvater
From the blurb of book 1:
Every year, Blue Sargent stands next to her clairvoyant mother as the soon-to-be dead walk past. Blue never sees them–until this year, when a boy emerges from the dark and speaks to her.His name is Gansey, a rich student at Aglionby, the local private school. Blue has a policy of staying away from Aglionby boys. Known as Raven Boys, they can only mean trouble.…
Song of the Lioness Series by Tamora Pierce
(This is part of the Tortall series, but is its own arc)
From the blurb of book 1:
In a time when girls are forbidden to be warriors, Alanna of Trebond wants nothing more than to be a knight of the realm of Tortall. So she finds a way to switch places with her twin brother, Thom. Disguised as a boy, Alanna begins her training as a page at the palace of King Roald. But the road to knighthood, as she discovers, is not an easy one. Alanna must master weapons, combat, and magic, as well as polite behavior, her temper, and even her own heart.…
The City of Ember By Jeanne DuPrau
From the blurb of book 1:
The city of Ember was built as a last refuge for the human race. Two hundred years later, the great lamps that light the city are beginning to dim. When Lina finds part of an ancient message, she’s sure it holds a secret that will save the city. Now, she and her friend Doon must race to figure out the clues to keep the lights on. If they succeed, they will have to convince everyone to follow them into danger. But if they fail? The lights will burn out and the darkness will close in forever.
The Once and Future King by T.H. White
(Now collected into one volume, this was originally a quartet)
From the blurb of book 1:
This is the tale of King Arthur and his shining Camelot; of Merlyn and Owl and Guinevere; of beasts who talk and men who fly; of knights, wizardry and war.
It is the book of all things lost and wonderful and sad; the masterpiece of fantasy by which all others are judged.