Ill admit I get bored by gore fest anime that seem like theyre trying too hard to be edgy, which is what I classify Hellsing as. Im more into whats classified as psychological horror or psychological thriller. Attack on Titan for example was great because it wasnt just scary or bloody, it introduced terrifying imagery and ways to die. So thats where my list is coming from.
Madoka Magica: looks are deceiving, watch the 3 movie series for the complete story arc
Psycho-Pass: season 1 is amazing, and 2 was good, but skip season 3 (one of the most disappointing seasons of any anime Ive seen)
Mirai Nikki: survival game anime with a yandere main character, which is someone who is obsessed with you in a psychopathic way
Parasyte: the others are correct, this one is pretty dark and also very deep
Death Note: maybe no one else mentioned it because it was too obvious
Drifters: I really enjoyed this one, but dont expect a conclusion
No matter our origin, we are all one family, we all share one planet, and we all need to feel loved and accepted. We are more alike than different.