Recommend me an apocalyptic manga/anime

Magical Girl Apocalypse is about a bunch of magical girl monsters coming down and killing everyone in their path. Very bloody and violent and dark. Very few people left alive. Written by the same guy who did the other magical girl horror, Magical Girl Site.

Koutetsujou no Kabaneri
felt like attack on titan but had different elements to its plot

Good tier: Shinsekai Yori, Gurren Lagann
Average Tier: Koutetsujou no Kabaneri, Owari no Seraph
Shit Tier: Guilty Crown, Black Bullet

Violence Jack

Hokuto no Ken

Shoujo Shuumatsu Ryokou

Gunnm

Blame

Seraph of the end
Aldnoah.zero
guilty crown
darling in the franx
chrome shelled regios
Sorry if I had a spelling error.
El Psy Congroo

My favorite is Angel's Egg, but it's not very action-packed.
Tenshi no Tamago
I also love YKK but it's focused on calmness and tranquility so there's even less action.
Yokohama Kaidashi Kikou
Yokohama Kaidashi Kikou
If you end up liking the iyashikei of YKK, also check out Shoujo Shuumatsu Ryouko.
Shoujo Shuumatsu Ryokou
If you really want one with a lot of action, try Alien 9.
Alien Nine

Dragon Head

This is gonna be a good thread. I love zombies but sadly, they weren't as good portrayed as in comics.

+1 to Shinsekai Yori.
(a bad one) I am hero.
(incompleted and ecchi) Highschool of the Dead

Apocalypse no Toride - there are giant beings like shingeki no kyojin
Green Worldz - at least it's not zombies
Gunjou Senki - not your typical apocalypse but this is quite good

On Your Mark Okay, sure, it's a music video for a song that's... honestly a bit too cheesy for it's own good. But that doesn't even matter when you've got Miyazaki doing some of his very best work narratively and artistically!

Nausica of the Valley of the Wind Speaking of, here's what many consider his first original breakout hit! I hear the manga is even better, but from what I remember, the movie works quite well on it's own. It's a classic for a reason, and every anime fan worth their salt needs to watch it at least once.

Girls Last Tour Just confirming what others have posted. This is probably the closest thing to what you've specified, and oh man, it's really something special. I will say that it's definitely not for everyone, but I say give at least the first volume (7 chapters or so) a shot, just to see if it clicks over time. It's a peaceful kind of apocalypse...

Neon Genesis Evangelion And finally, to completely flush any credibility I once had down the toilet, I'll enthusiastically recommend Neon Genesis Evangelion and it's must-see final act, End of Evangelion. Go in as blind as possible and with an open mind in regards to philisophical musings and you'll have a pretty good time. The manga is pretty interesting (it's sorta like an alternate cut on the same content), but I'd advise you to avoid the Rebuild movie series, as they just lack the same bite the OG had, y'know?

Kabenari of the iron fortress ( same director of Attack on titan )
Owari no Seraph
Black bullet
Guilty Crown

Thanks for all the recommendations, didn't expect to get this many, I will try to check all of them.

I would also recommend :

Texhnolyze
Ergo Proxy
Akira
Casshern Sins