Welcome to the forums, hope you enjoy it here
Of the series you mentioned, I’ve seen FMA:B, Hellsing Ultimate, Death Note and enjoyed them to varying degrees. Dark/horror as a genre usually isn’t my favorite, but there are a number of series I enjoyed that could be categorized that way:
Shiki
Re:Zero
Higurashi: When They Cry
Fate Zero
Paranoia Agent
Dororo
Monster
Dorohedoro (dark humor)
Sounds cool. Feel free to share. I’m not artistically talented but some folks here are.
Hope you find things that interest you