Old anime recomendation

I'm going to start an old anime marathon today and I need recommendations. On the list I have Akira, Ghost in the Shell, Cowboy Bebop, Mononoke Hime and My Neighbor Totoro. I've seen the rest from Miyazaki. I need more! Also, a little out topic, do you know of any anime series or movie that has a very dark, twisted or creepy story with lots of blood and some horror too? I'm in the mood for something like that.  
Thanks!

Horror is not my strongpoint, so forgive me for outright ignoring that part. (Though I will ask if you've seen Higurashi: When They Cry? I saw a few clips that freaked me out a while back).

Old anime is otherwise my specialty, though, so I have a lot I can recommend:

Mecha:

Mobile Suit Gundam
Macross
Dougram
Armored Trooper Votoms
Blue Comet SPT Layzner
Martian Successor Nadesico
Heavy Metal L-Gaim
Aura Battler Dunbine
Visions of Escaflowne
Super Dimension Century Orguss
Orguss 02
Space Runaway Ideon
Zoids
Evangelion

Super Robot:

The King of Braves GaoGaiGar + GaoGaiGar Final
Big O
Giant Robo
Getter Robo Armageddon
Dancougar‎

Sci-Fi:

The Legend of Galactic Heroes
Banner of the Stars
Outlaw Star
Trigun
The Irresponsible Captain Tylor
Iria: Zeiram The Animation
Jin-Roh: The Wolf Brigade
The Third: The Girl With the Blue Eye


Fantasy:

Berzerk
Slayers
El-Hazard
The Record of Lodoss Wars
Tenchi Muyo
Magic Knight Rayearth

Action Shounen:

Rurouni Kenshin
Yu Yu Hakusho
Hunter X Hunter
Dragon Ball
Fist of the North Star
Saint Seiya
Shaman King

I'll add more later...

Yes I've seen Higurashi and it's pretty good.

Wow thank you so much! I've only seen a few of those like Evangelion, Trigun and Dragon Ball. This marathon is going to last longer than I though. I started watching anime a few years ago so I have missed on most of those old series and I have the best site in the world that has the all! I am one happy anime nerd right now.

I still got at least 20 more to recommend, bro:

Aim For The Top: Gunbuster
Captain Harlock
Galaxy Express 999
Raxephon
B*stard!! (undo the censoring yourself)
Megazone 23
Tekkaman Blade
Dear Brother (Oniisan e)
Rose of Versailles
Revolutionary Girl Utena
Haibane Renmei
Ninja Scroll (movie)
Hajime no Ippo
Slam Dunk
Aim for the Ace
Kimagure Orange Road
Maison Ikkoku
Ramna 1/2 (just the first few seasons!)
Urusei Yatsura (Probably just the first few seasons, too)
Ah! My Goddess (OVA)
Card Captor Sakura

Might even add a few more later if I remember them...I recall having a lot more fantasy anime than that. Might be missing a sci-fi or two as well...

You haven't seen Totoro yet? :O Totoro is essential! It's the Japanese Bambi, in the sense that it's the only other cartoon that's ever made me cry.

Of the TV animes, I can't recommend Fist of the North Star enough. Because it's post apocalyptic it's kinda horror in the sense that what they get up to is quite dark and brutal, and it's one of the most influential animes of all time, so you should see it just so you know what everyone's talking about