Thought I'd type up a quick post linking some, in my opinion, quintessential DSBM bands. DSBM is pretty self-explanatory: black metal (typically atmospheric black metal) with a central focus of depression, suicide, loneliness, despair, anger, hatred, sadness, and many more similar emotions. It's often long and repetitive, but not always; it's actually a very varied genre.
Here are my top bands, with links to my favorite album of theirs.
Make a Change... Kill Yourself is what I consider peak DSBM: raw, atmospheric, and drenched in emotion. The band's name, titles, and lyrics are all very self-explanatory, but you don't need to be poetic and deep to hit hard emotionally.
Leviathan is what I think of as the peak of American black metal, with his first album The Tenth Sub Level of Suicide being another quintessential DSBM album. Most of Wrest's (Jef Whitehead) other work as Leviathan isn't DSBM, though it dances around it. Tenth Sub Level channels much more anger and hatred.
Shining is another angry and hateful band, with Halmstad (full title Halmstad (Niklas angående Niklas)) being a monument of hatred and aggression. Shining is the work of Niklas Kvarforth, who claims to aim to make people hurt themselves and kill themselves with his music, something that clearly comes across.
Xasthur is another pillar of American black metal. It's hard to choose a record to link because they're all brilliant, but they're all very similar; no matter what album you put on, you'll be transported to a extremely dissonant and alien world of sadness and anger.
Lifelover is an interesting one; they definitely fit into DSBM, but have many elements of post punk, post rock, post metal, and are generally better labeled as depressive rock in my opinion. Lots of imagery of drugs, alcohol, and urban Swedish life.
Psychonaut 4 is similar in its topics, but has a very different, though similarly post metal, sound. Hailing from Georgia, they have lyrics in Georgian, Russian, and English, conveyed through shrill, piercing screams unlike any other band.
Këkht Aräkh isn't typically linked into this genre, but he fits very well in my opinion. Dark, gothic, romantic black metal that tells stories of love, sadness, and loneliness through concept albums of vampires seeking love. There's a reason Pale Swordsman is a phenomenon.
NONE is probably the closest band you'll find to Xasthur, but they're still entirely different. Very dark, bleak, atmospheric, and cold dirge-like songs fill their albums.
I'll add more to this post in the future, but these bands are a good starting point for anyone curious about the genre.