There used to be a time when anime was all about hard-ass motherfuckers, scantily-clad hot chicks, and gallons of blood. Sadly, those days are gone, as anime sucks, right now, but we can still remember the good old days and watch bad guys explode with classic anime DVDs.
One in particular from the 1990s comes to mind. Though I haven't seen the entire series (or even close to half the series) Berserk is definitely one of the most brutally violent anime that's actually any good. The anime and manga follow the life of a man known only as Guts, who is born into the life of a mercenary. In his lifetime, he kills scores of men, is raped as a child, cuts off his own arm, loses an eye, is branded for death by demons, and is forced to watch the woman he loves get raped by his mercenary commander, who is transformed by the very same demons. Like I said, it's pretty brutal. After this, Guts goes on a crusade to kill any demon he comes across. With a prosthetic iron arm, fitted with a repeating crossbow, and his huge ass sword, Dragonslayer, Guts makes "blood-gore salad" with his enemies like he was a food processor.
Of course, with a name like Berserk, you know the hero has some anger issues. Later on, Guts' rage manifests into a demon called The Hellhound, who encourages Guts to commit further atrocities while in his battle lust, which is caused by his "Berserker Armor." Despite harboring this demon of his own hate, Guts struggles to hang onto any remnants of humanity left in his soul.
Despite being well received by critics, the show and the manga never really became popular in the US, most likely due to its extremely adult nature. However, it did reach enough of an audience to see the American release of the anime, manga, and a Dreamcast game, which came out in 2000. So, if you are a fan of some of the older anime and love brutality, definitely look into this series.