Berserk.

Berserk is far and away my favorite manga, and the anime isn't bad either. It's been around for quite a while, so I'm surprised no one has made a thread about it before. It's about a man named Guts who travels around his world with a band of mercenaries called The Hawks. Guts carries a massive 7' sword, which he wields with speed and accuracy. While this seems like a cliche, there's actually a reason for it. Berserk is unique in that it's very, very gritty. Guts' origin is a very good example of this, and while I suggest you read the manga and find out for yourself, I'll put it in a spoiler tag in case you don't care.

Spoiler:

Guts' mother was hanged while pregnant with him, and just as she was being hanged, Guts fell out. He, too, was nearly hanged by his umbilical cord. However, he was picked up by a band of mercenaries, who basically forced him into a life of war and suffering. Ouch, dude.

As for how to get it: Volumes 1-30 have been translated, and can be found on... the internet. I don't have any exact sites, sadly, and I don't remember where I got it, but I'm sure it'll only take a little searching. Alternatively, if you're against downloading stuff or just like spending money, Dark Horse has published several volumes.

Jam it back in, in the dark.