There's something special about committing to a truly massive series. You don't just read the books—you live with them. Characters become like old friends. The world becomes a second home you can visit whenever you need escape. The investment pays dividends that shorter series can't match.
But not every long series justifies its length. Some peter out, some decline in quality, some just start padding after a while. The series on this list maintain quality across their runs, rewarding readers who stick with them for 20, 30, or even 40+ books.
What Makes a Long Series Work?
Maintaining quality over 20+ books requires: characters who can sustain reader interest across decades of fictional time, a world rich enough to keep exploring, an author who stays interested and doesn't phone it in, evolution—the series should feel different in book 20 than book 1, while still feeling like the same series, and ideally, entry points where new readers can jump in without starting at book 1.
1. Discworld by Terry Pratchett (41 books)
The gold standard for long fantasy series. Set on a flat world carried through space on the backs of four elephants standing on a giant turtle, Discworld evolved from pure parody into some of the sharpest social commentary in fantasy. The beauty is that you don't need to read all 41—the series has multiple sub-series (the Watch, the Witches, Death, etc.) that can be read independently.
Start with: Guards! Guards! for the Watch books, Wyrd Sisters for the Witches, or Mort if you want to meet Death.
2. The Wheel of Time by Robert Jordan and Brandon Sanderson (14 main books)
One of the most ambitious fantasy series ever attempted, following the Dragon Reborn as prophecy and politics converge toward the Last Battle. Yes, it slows down in the middle, but the payoff in the final books (completed by Sanderson after Jordan's death) is immense.
This one you really should start at book 1 (The Eye of the World) and commit.
3. In Death by J.D. Robb (60+ books)
Nora Roberts writing as J.D. Robb delivers near-future procedurals following Eve Dallas, a homicide detective in mid-21st century New York. Remarkably, the series maintains quality across six decades worth of books. The mysteries are solid, Eve's character development is genuine, and the supporting cast grows richer with each entry.
Start with: Naked in Death, book 1. The early world-building is worth experiencing.
4. Jack Reacher by Lee Child (28+ books)
The quintessential airport thriller series. Reacher is a former military investigator wandering America, finding trouble wherever he goes. The formula rarely varies but rarely disappoints. These are pure entertainment, and Child knows exactly what he's doing.
Start with: Killing Floor (book 1) or The Affair (prequel) or honestly any book that catches your interest.
5. Longmire by Craig Johnson (20+ books)
Sheriff Walt Longmire solves crimes in Wyoming's Absaroka County, often involving the nearby Cheyenne reservation. The series combines mystery with beautiful writing about the American West, complex exploration of Native American issues, and a protagonist who ages realistically across the books.
Start with: The Cold Dish, book 1.
6. The Dresden Files by Jim Butcher (17+ books, ongoing)
Harry Dresden is Chicago's only professional wizard, taking cases that the police can't handle. The series starts as fun noir-flavored urban fantasy and evolves into something much more epic, with escalating stakes and deepening mythology. The audiobook versions, narrated by James Marsters, are particularly beloved.
Start with: Storm Front (book 1), though many fans suggest starting with book 3 (Grave Peril) if book 1 doesn't grab you.
7. Stephanie Plum by Janet Evanovich (30+ books)
Stephanie is a bounty hunter in Trenton, New Jersey, perpetually caught between two love interests and perpetually getting into ridiculous situations. These are popcorn books—not deep, not literary, just reliably entertaining. The humor hasn't changed much in 30 books, but if it ain't broke...
Start with: One for the Money.
8. Alex Cross by James Patterson (30+ books)
Washington D.C. detective and psychologist Alex Cross hunts serial killers and other dangerous criminals. Patterson's short chapters and constant cliffhangers make these incredibly propulsive reads. Quality varies more than some other series, but the best entries are genuinely thrilling.
Start with: Along Came a Spider.
9. Honor Harrington by David Weber (20+ main books)
Military science fiction following Honor Harrington's rise through the Royal Manticoran Navy. Often described as "Horatio Hornblower in space," the series delivers epic space battles, political intrigue, and one of the great military commanders in SF. The later books get very dense with politics, but fans eat it up.
Start with: On Basilisk Station.
10. Brother Cadfael by Ellis Peters (21 books)
A 12th-century Benedictine monk who was formerly a soldier and crusader solves murders in medieval Shrewsbury. Historical mysteries don't get much better than this. The setting is richly realized, Cadfael is wonderful company, and the mysteries are fairly clued.
Start with: A Morbid Taste for Bones, though each book stands alone.
Is It Worth the Commitment?
Not every reader wants to commit to a 20+ book series, and that's fine. But for those who do, the rewards are real. You get to watch characters age and change. You develop relationships with fictional people that span years of your own life. You get to return to worlds that feel as familiar as home.
Pick one series that sounds appealing and give it a real chance. You might find your next reading obsession.
— mrod