[Lawtan]

*looks into Crunchyroll*
...out of 22 anime series I'm interested in, it had 3...
.-.

Anime series:

Another*
Blue Gender
Blood-C
Claymore
Corpse Princess <3
Corpse Party
Danganronpa: The Animation
Elfen Lied
Fairy Tail*
Fullmetal Alchemist Brotherhood
Ghost Hunt <3
Inuyasha
Mobile Suit Gundam Wing <3
Mirai Nikki (Future Diary) <3
Monster Rancher
Puella Magi Madoka Magica*
Shiki
Spice and Wolf <3
Tears to Tiara
Tower of Druaga
Umineko no Naku Koro ni <3
Wolf`s Rain

Disclaimer:

Law likes horror/supernatural, but not absolute/badly done tragedy. Sort of a "go through literal hell to have at least hope in the end" thing. That said, Blood-C, Shiki, Corpse Party, and possibly Another aren't positive endings. Blood-C has character, Shiki is a tragedy, Another just sort of ends...
Elfen Leid is a bit like Blood-C. Umineko is a roller-coaster murder mystery.
Corpse Princess is largely allegory for suicidal ideation & overcoming it.
Tears to Tiara & Tower of Druaga use mythology (Arthurian and Sumerian respectively) and science fiction...but sadly are often...ehm... *Law is embarrassed*