Which older / more serious fantasy books do you recommend?

[Eredin]

I'm looking for some adult fantasy book with an extensive plot, curses, sex, brutal descriptions, and maybe some bigger battles. It's supposed to be something like The Witcher or a Song of Ice and Fire.
So far, apart from the above-mentioned books, I have read the Acts of Caine and the rest are more "innocent" items.

For now, I'm keeping an eye on the Black Company and the Night Angel Saga. Does the latter in particular meet my requirements?

[Hawking]

Malazan Book of the Fallen by Steven Erikson

[fabulousfreesia]

Yes, but for a better understanding of what's going on, it's a good idea to combine this series with

Novels of the Malazan Empire by Ian Cameron Esslemont

And to supplement some threads, I recommend it

The Tales of Bauchelain and Korbal Broach.

[Oneia]

I'm looking for some adult fantasy book with an extensive plot, curses, sex, brutal descriptions, and maybe some bigger battles. It's supposed to be something like The Witcher or a Song of Ice and Fire.
So far, apart from the above-mentioned books, I have read the Acts of Caine and the rest are more "innocent" items.

For now, I'm keeping an eye on the Black Company and the Night Angel Saga. Does the latter in particular meet my requirements?

I recommend the series "Tales from the Meekhan Borderland" by Robert Wegner.

[Rincewind1]

I'm looking for some adult fantasy book with an extensive plot, curses, sex, brutal descriptions, and maybe some bigger battles. It's supposed to be something like The Witcher or a Song of Ice and Fire.
So far, apart from the above-mentioned books, I have read the Acts of Caine and the rest are more "innocent" items.

For now, I'm keeping an eye on the Black Company and the Night Angel Saga. Does the latter in particular meet my requirements?

Lord of the Ice Garden

[Supergirl]

I'm looking for some adult fantasy book with an extensive plot, curses, sex, brutal descriptions, and maybe some bigger battles. It's supposed to be something like The Witcher or a Song of Ice and Fire.
So far, apart from the above-mentioned books, I have read the Acts of Caine and the rest are more "innocent" items.

For now, I'm keeping an eye on the Black Company and the Night Angel Saga. Does the latter in particular meet my requirements?

I don't know if adult enough it will meet your expectations, but I can highly recommend Peter V. Brett's Demon Cycle. It starts out loosely at first, but over time the books take on a heavier vibe.

[Dangerous]

I'm looking for some adult fantasy book with an extensive plot, curses, sex, brutal descriptions, and maybe some bigger battles. It's supposed to be something like The Witcher or a Song of Ice and Fire.
So far, apart from the above-mentioned books, I have read the Acts of Caine and the rest are more "innocent" items.

For now, I'm keeping an eye on the Black Company and the Night Angel Saga. Does the latter in particular meet my requirements?

Kane, the Mystic Swordsman by Karl Edward Wagner

[Gor]

From here already mentioned with a clear conscience I can recommend:

1. Lord of the Ice Garden - Jarosław Grzedowicz
2. Tales from the Tales from Meekhanese Border - Robert M. Wegner
3. First Law - Joe Abercrombie

They are all full-blooded fantasy, with no princesses, ponies and unnecessary kiri-kiri. Besides, reading them is a real pleasure.

[Leriel]

I will recommend the above, i.e.
Lord of the Ice Garden
Demonic cycle (infinite, so you have to wait; /)
The series about the king's king by P. Rothfuss - in my opinion, one of the best fantasy books recently, also unfinished yet
And for me, a real gem - the Storm Light Archive series
two great volumes, a brilliant world, and I envy the first reading
you will not understand everything, but it is a miracle! - as above, we have to wait for the end for many more years

from this author, I will recommend the series The Last Empire and the series Avengers (both may not be super "grown-up" but it is worth reading
in the Avengers there is an interesting world where some people got superpowers but they did not become superheroes but all super-tyrants, that is, as I always imagined it would happen if someone got such powers

when it comes to the Sage of the Night Angel, somehow after the 1st volume I passed my desire to read, but I will definitely be back
and the Black Company - after a few volumes you feel weary

and if you want something less serious this Cycle: Detective Garrett is a good read

[Triss Merigold]

I also highly recommend The Stormlight Archive,
I also recommend The Lightbringer Series by Brent Weeks