Can anyone recommend a series or trilogy that is hard to put down?

CJ Sansom's Shardlake books are brilliant. If you liked Ken Follets ones you might like these.
Also Philip Pullman's His Dark Materials.
Game of Thrones?

Poldark?

Elena Ferrante's Neapolitan novels.

I second the Neopolitan series

Robin Hobb. Start with the Assassin's Apprentice.

I loved the Hunger Games books, the films not so much, but the books were gripping.

Also loved The Girl with the Dragon Tattoo series.

Was also going to suggest The Girl with the dragon tattoo series. I’m not an avid reader but I found these really held my attention.

Following with interest!

Philip Pullman’s His Dark Materials

Robin hobb!!! Amazing amazing. Assassin series is fabulous.

A friend loaned me a Ken Follett book and I read it on a flight at Christmas. It was fantastic. I was even more excited to discover it's part of a trilogy. The first book is called Fall Of Giants (about WW1) and the second is Winter Of The World (about WW2), I'm thinking of ordering it as a present to myself when the January paycheck comes through. I don't know what the third book is called and I can't remember the title of the trilogy (sorry!) But I strongly recommend Fall Of Giants. Author is Ken Follett.

Happy reading, whatever you choose, OP.

I second the robin Hobbs trilogies, all three trilogies about fitz, the live ship traders trilogy and the rainwild chronicles. They’re all amazing and I cried my eyes out after the last book in the series.

If you like darker fantasy stuff then the night angel trilogy is good! I’d basically recommend anything by Brandon Sanderson and Brent weeks. Also mark Lawrence as well, he has some great trilogies.

Just read a trilogy by an author called N K Jemisin - the broken earth trilogy, which was fantastic!

For longer series or trilogies not yet complete I’d recommend:
Pathrick rothfuss - the king killer chronicle
The stormlight archive
The light bringer series
The gentlemen bastards sequence

Oh and books by Trudi Canavan, she has quite a few trilogies and companion trilogies too that I enjoyed.

Finally- his dark materials by Phillip Pullman. Favourite series ever!

Sorry, OP, I didn't see that you'd already read Ken Follett.

I agree with the previous posters who've recommended Stieg Larsson's Millennium trilogy. Not my usual thing but I was absolutely gripped.

I also like the Jack Reacher series by Lee Child and Inspector Rebus books by Ian Rankin.

Robert Harris' Imperium trilogy if you're interested in Ancient Rome.

Pretty much any Bernard Cornwell but I especially enjoyed his Arthur trilogy and his Uhtred/Alfred series (ongoing).

Seconding the Shardlake series by C J Sansom. Really enjoyed those.

I also liked the Cazalet series by Elizabeth Jane Howard.

All Souls Trilogy by Deborah Harkness
It's all about Supernatural beings, like vampires and witches and forbidden love...

The millennium trilogy

I'm really enjoy the GoT books, finding them hard to put down.

Kelley Armstrong has written some good supernatural series

Stephen leathers jack nightingale series, it supernatural, not my usual type of books but gave it a go and found I couldn't put it down.

The Dark Eden trilogy by Chris Beckett

If you like crime books, give the L.J Ross series a try. There's 7 books in the series, I've enjoyed every one.

the Dark Tower series by Stephen King. it's brilliant in parts, a bit rubbish sometimes and gets a bit out of hand around book 5 but overall I loved it. contemplating a third read...