Horror!

[angel.shade]

But uhm... not your typical "excuse to see the female lead in a wet t-shirt" style horror we seem to have over on this side of the world.

More "WTF" factor, more disturbing and really twisted things happening. The more f'd-up stuff, the better.

Something more f'd up than Elfen Lied. =p

[Frans]

Try Higurashi. It's actually have a several arcs which the arcs are alternate story with the same character.
I have several other suggestion on my head.. maybe later.

[MaxwellDemon]

Higurashi seconded as well. XD
It has enough "what the flying crap is that?!" moments even though horror is really more of a tertiary genre through out the series.

[angel.shade]

I'm currently watching Higurashi. =p

The WTF factor is further heightened by the cutesy character designs that would be more fitting in a romantic comedy slice-of-life series. D=

[miaka]

ghost hunt - horror/mystery based from novel

[SeijiSensei]

I sound like a broken record these days, but try Mononoke.

[Zippicus]

You could try Jigoku Shoujo and Jigoku Shoujo Futakomori there are some seriously messed up stories going on there. They do a pretty good job of bringing out the worst in humanity.

[Frans]

@Seiji or anyone else that have watch Mononoke and Ayakashi...
btw, since I haven't watch Mononoke, I noticed that it have Bakaneko arc... is it the same as the Bakaneko arc in Ayakashi or different?

[Mnemosyne]

It's a different Bakeneko...

Anyway, Petite Cossette is horror-esque and Ayakashi is awesomely awesome and Monster is really good, although it's more suspense than horror... and of course, I agree on Mononoke, Higurashi and Jigoku Shoujo...!

[angel.shade]

Higurashi is totally succeeding at breaking my brain. o____________o

I'm so confused and creeped out, but at the same time I'm all ZOMG KILLER LOLIS. rofl.

[gaguri]

Originally Posted by frans

btw, since I haven't watch Mononoke, I noticed that it have Bakaneko arc... is it the same as the Bakaneko arc in Ayakashi or different?

There are two different series, Mononoke and Ayakashi (you probably already know that, but just in case). Now, there is a Bake Neko (not BakA Neko...although I sometimes wish there was one...) arc for both Ayakashi and Mononoke. They're two different arcs. Although Bake Neko arc of Mononoke have characters and story very similar to the one in Ayakashi, they are executed in a very different manner. Both of them are very good in their own way, but a popular opinion is that Ayakashi's Bake Neko arc is better (something I agree with), if only by very little.

My recommendation is to skip two mediocre arcs of Ayakashi, and watch the aaaaammmmmaazing Bake Neko arc of Ayakashi, and the equally amazing Mononoke series.

As for other horror recommendations worth considering,

Higurashi and Perfect Blue for intense and neurotic psychological thriller. Something that makes you jump from your seat and have sweat run down your spine. MONSTER is also gold, but has lot more in character and story department.

Vampire Princess Miyu OVA for more elegant, beautiful sense of horror. It's bit old though, so approach with caution.

Le Portraite de Cossette for a very beautiful and gothic horror. It's directed by Shinbo, so the story may be bit confusing, but has amazing art, animation, music and overall direction.

Hundred Stories is bit weak in its storytelling, but has quite interesting animation style for those who like their animes unconventional. It's episodic, so just watch the first episode to decide whether to continue or drop.

[Frans]

Originally Posted by gaguri

There are two different series, Mononoke and Ayakashi (you probably already know that, but just in case). Now, there is a Bake Neko (not BakA Neko...although I sometimes wish there was one...)

My bad... It just seemed more natural to write baka than bake...

As for my other suggestion, maybe you could try Boogiepop Phantom and Paranoia Agent.. I don't think those two anime fall into the horror category.. but it's disturbing and twisted... and rather dark.

Another suggestion would be Narutaru... At first it just another anime, but by the time you watch the ending, it's pretty messed up.

And Gantz, if you ignore the ending, is kinda messed up too... but it's more of an action anime, maybe closer to Elfen Lied than Higurashi.

[Zippicus]

Originally Posted by Frans

Another suggestion would be Narutaru... At first it just another anime, but by the time you watch the ending, it's pretty messed up.

Just a note on Narutaru, I watched it on a recommendation, and I enjoyed it for the most part. Just be aware that watching the anime will not give you the whole story. So if you're into watching half a story then it's fine, but if you want any kind of a conclusion, read the manga instead.

[psgels]

If you want a really disturbing story (even worse than Higurashi), then go for Shigurui. I'm actually surprised that that one hasn't been mentioned yet.

[sothis]

Mmmm horror, my specialty.

Instead of explaining what they are about, just check out the links! I am very picky about horror, but can vouch for how awesome these all are.

Pet Shop of Horrors
Requiem from the Darkness (aka Hundred Stories, already mentioned above)
Puppet Princess
Mermaid's Forest TV (also the OVA and Scar)

and in a strange sort of way, Judge

[Deathkillz]

Something that hasnt been mentioned ~ Blue Gender

one of the most fcked up, shit scary series next to gantz ive seen

[Zu Ra]

Check out this anime called Hundred Stories

[White Manju Bun]

Hmm not really a "wtf" anime but xxxHolic along with the movie had some creepy scenes. I seconded Ghost Hunt (of course) along with Mononoke. Also if you watch Narutaru you might try Bokurano since its by the same mangaka. Again not a "wtf/horror" but definitely pyschology.