Loren's Music Room

If you want moody try Debussy.
however he’s not technically from the classical era.
others that are dark that I like are:
Stravinsky
Wagner

prelude by A.F.I.

moonlight sonata

you can get all the classical music from limewire mostly try anime soundtracks i found most of them quite good

yes. i do… Its all piano look up..
Prelude in C sharp minor by Rachmaninoff

its actually from a part of the movie "The Exorcism of Emily Rose"

Oh Fortuna by Mozart.

It’s pretty popular, but brooding like in my opinion.

Scriabin’s Sonatas No.6 and No.9 "Black Mass." Scriabin’s 6th sonata is so menacing that Scriabin never performed it in public because he felt it was nightmarish, murky and mischievous. Indeed, Beethoven’s Moonlight sounds cheerful compared to this. The nickname of Scriabin’s penultimate piano sonata speaks for itself and is a work that has a harsh and grotesque.
I take it you are referring to Beethoven’s Piano Sonata No.14 in C sharp minor. There are few pieces with quite the same feel as the ubiquitous Moonlight and only the first movement has that funereal overtone. (The second and third movements are totally different in mood – the second is rather sunny and the final movement, violent in its anger and anxiety).
"O Fortuna" is NOT by Mozart by the way (It is a 20th Century piece by Carl Orff).
And Yann Tiersen’s music is not classical in any way.

A lot of Chopin’s work fit your description.
For example, Op.66, Tantaisie-Impromptu in C sharp minor.
Mussorgsky, too. His "Pictures at an exhibition"(especially "Promende-Limoges: the tombs, and conversation with the dead").
Mussorgsky’s "Night on the Bare Mountain" feels dark and kind of scary,too.
Mussorgsky’s are not piano, though. It’s played by a symphony orchestra.
Just curious, why are you looking for this type of classical music?

Any Beethoven Sonata 2nd movement that’s in a minor key