Science fiction thrives in series form. The best sci-fi book series don’t just tell a story—they build entire universes, challenge your imagination, and keep you turning pages across multiple volumes. Whether you’re a fan of futuristic warfare, alien diplomacy, or deep philosophical questions, these sci-fi sagas offer something unforgettable. Here’s a ranked list of the best sci-fi book series of all time.

1. Dune Series by Frank Herbert

Why It’s #1:
Dune is the gold standard of science fiction. Combining politics, religion, ecology, and philosophy, this epic saga is as deep as it is thrilling. Set on the desert planet of Arrakis, it explores power, prophecy, and survival across generations.

Start With: Dune
Books: 6 main books by Frank Herbert (plus prequels/sequels by his son)

2. The Expanse Series by James S.A. Corey

Why It’s Great:
This modern space opera blends political intrigue, realistic science, and gripping characters. From asteroid belt colonies to mysterious alien tech, The Expanse is fast-paced, emotional, and surprisingly grounded.

Start With: Leviathan Wakes
Books: 9 novels + short stories and novellas

3. Foundation Series by Isaac Asimov

Why It’s Legendary:
A sweeping saga of the rise and fall of a galactic empire, Foundation introduced the concept of psychohistory—predicting the future using math. Deep, philosophical, and visionary, it’s essential reading for any sci-fi fan.

Start With: Foundation
Books: 7 core books (plus tie-ins with Asimov’s Robot series)

4. Hyperion Cantos by Dan Simmons

Why It Stands Out:
Each book blends genres—horror, mystery, military sci-fi, and theology—into a literary and emotional experience. Inspired by The Canterbury Tales, Hyperion is rich, layered, and unforgettable.

Start With: Hyperion
Books: 4

5. The Three-Body Problem Trilogy (Remembrance of Earth’s Past) by Liu Cixin

Why It’s Mind-Blowing:
Hard sci-fi at its finest. This Chinese series explores first contact, alien civilizations, and cosmic-scale threats with bold ideas and scientific precision. It’s thought-provoking and intense.

Start With: The Three-Body Problem
Books: 3

6. Old Man’s War Series by John Scalzi

Why It’s Fun:
Fast, funny, and action-packed, this military sci-fi series has heart. Scalzi blends sharp dialogue with big ideas about aging, war, and identity—without ever feeling too heavy.

Start With: Old Man’s War
Books: 6

7. Wayfarers Series by Becky Chambers

Why It’s Different:
Hopeful, inclusive, and deeply character-driven, Wayfarers is about people as much as space. It’s cozy sci-fi—perfect for readers who want emotion and optimism with their interstellar travel.

Start With: The Long Way to a Small, Angry Planet
Books: 4

8. Robot Series by Isaac Asimov

Why It’s Influential:
With his famous Three Laws of Robotics, Asimov laid the groundwork for much of modern sci-fi. These short stories and novels explore ethics, logic, and what it means to be human.

Start With: I, Robot
Books: Several story collections and novels

9. Red Rising Series by Pierce Brown

Why It’s Intense:
Combining dystopian fiction with Roman-inspired politics, Red Rising is brutal, fast-paced, and full of betrayal. It’s The Hunger Games meets Game of Thrones in space.

Start With: Red Rising
Books: 6 (and counting)

10. Revelation Space Series by Alastair Reynolds

Why It’s Complex:
This series blends hard science with gothic atmosphere. Reynolds builds a dark, sprawling future full of AI, alien relics, and deep-space horror. It’s intense and richly detailed.

Start With: Revelation Space
Books: Multiple novels and short stories

11. Vorkosigan Saga by Lois McMaster Bujold

Why It’s Beloved:
Blending adventure, politics, and family drama, this long-running series follows Miles Vorkosigan—a brilliant, flawed, and unforgettable protagonist. Full of heart, humor, and intrigue.

Start With: Shards of Honor or The Warrior’s Apprentice
Books: 15+ (can be read in publication or chronological order)

12. Culture Series by Iain M. Banks

Why It’s Bold:
Set in a post-scarcity utopia ruled by AI, the Culture series challenges ideas of war, morality, and freedom. Each book stands alone but adds to a larger philosophical picture.

Start With: Consider Phlebas or The Player of Games
Books: 10

Final Thoughts

The best sci-fi book series pull you into fully realized worlds and keep you hooked with evolving plots and characters. Whether you want philosophical space epics like Dune, fast-moving thrillers like Red Rising, or emotional tales like Wayfarers, there’s a sci-fi series for you. Start with what excites you—and prepare to explore galaxies of imagination.