Renu sundriyal  I agree with the comment that the question is too vague. But I want to shift the conversation away from the notion of ‘musically badass’, and onto the notion of ‘performatively badass’. It’s one thing to compose a raucous piece of music and have it performed in front of a sophisticated paying audience who are primed to be receptive to what you’re doing—which is pretty much what every composer thus far did. From Beethoven to Stravinsky, they may all have been writing pounding or aggressive music—but they were doing it for an audience that prided itself on being cool enough to take what these composers were giving them. In other words: the badassery is purely aesthetic. But suppose that the consequences of making the music were potentially far worse than just people hissing through their keys at you. (That’s what happened to Arnold Schoenberg with his Chamber Symphony No. 1. Or slightly mixed reviews the next day, which happened to Beethoven with Symphonies No. 3 and 9. Contrary to legend, nobody ‘rioted’ at the first performances of Stravinsky’s Rite of Spring. There was a shouting match in the audience but it died down, and the work—which was the score of a ballet—ended up getting several curtain calls.) Suppose that making the music at all could get you thrown in prison? Or worse? Suppose that the very act of composing and publishing the music was, in fact, badass? In that case, I propose a rather different set of compositions as the most badass. Come back with me to late 16th/early 17th century England.

Renu sundriyal 

Some of the greatest dark classical music works include:

Beethoven's Symphony No. 9 ("Choral") - The famous finale of this symphony, with its dark and ominous minor key passages, is considered one of the most powerful and emotionally intense works in the classical repertoire.

Verdi's Requiem - This large-scale choral work is infused with a deeply solemn and foreboding atmosphere, evoking themes of mortality and the afterlife.

Shostakovich's Symphony No. 5 and No. 8 - These symphonies by the Russian composer feature brooding, unsettling tonalities that capture the oppression and turmoil of the Soviet era.

Ligeti's Requiem and Lux Aeterna - These 20th century avant-garde works utilize dissonant harmonies and eerie, atmospheric textures to create a profound sense of darkness and unease.

Gorecki's Symphony No. 3 ("Symphony of Sorrowful Songs") - This powerful work draws on Polish folk melodies and religious themes to express deep grief and mourning.

Mahler's Symphony No. 6 ("Tragic") - The ominous hammer blows in the finale of this symphony are considered one of the most haunting moments in the classical canon.