Hellsing's vampire antihero Alucard is an arrogant, bloodthirsty creature of the night who takes great pleasure in torturing and humiliating any lower-class vampire that thinks they have a chance against him. However, despite all of his sadism, he shows a surprising amount of humanity. When it comes to his boss and his underling, he shows a softer side, and when confronted with his own acts of monstrousness, he feels a deep sense of regret. Alucard is definitely a monster, but he's also the human character in the series.
Alucard fights with extreme ferocity, and he takes great pleasure in dragging out his fights against people who claim the title of "vampire." He makes sure to humiliate them, to make them grovel and beg for death. At the same time, however, he shows a large amount of respect for anyone that chooses to fight to live. When he first meets Seras, he shoots her through the chest to kill a homicidal vampire priest.
However, he doesn’t leave her to die -- instead, he holds her hand and comforts her before asking if she would accept becoming a vampire. He sees her will to live in her eyes, and it speaks to his humanity. He takes on the role of mentor and father-figure for her, often reminding her that she will never become a full vampire until she drinks human blood. It isn’t until she does so that he finally calls her by her real name instead of “Police Girl.”
Alucard's relationship with his master Integra also demonstrates his very human complexity. He acts arrogantly and at times antagonistically with her, but he also shows her a high degree of respect, even when she was a child. After she awakened him in the estate dungeons, the first thing he did was to bow and acknowledge her role as the head of Hellsing, despite her young age. He watched her grow up and mature into a young woman, helping her develop the skills needed for someone in her position. We see how deep their bond goes when Alucard begins to fade away after absorbing Schrodinger and Integra begs him not to leave her.
Alucard’s tragic backstory explains a lot of his complexity. Growing up, he was enslaved and abused by Ottoman rulers. He grew up becoming the feared Vlad the Impaler, killing people from the Turkish side and his own. His defeat at the hands of the Turks led to him becoming a vampire, as he drank blood off of the battlefield in defiance of God and his fear of death. He wanted to live, even if that meant becoming a monster.
Perhaps the best demonstration of Alucard's humanity is in his relationship with Father Alexander Anderson. This relationship is one of respect and rivalry. He sees much of himself in Anderson and hopes that Anderson will be able to defeat him as a human. However, his hopes are dashed when Anderson impales himself with Helena’s Nail, turning him into a thorny-vine human hybrid. Alucard begs Anderson to fight him as a human, but his pleas go unheeded. The fight continues, with Anderson gaining the upper hand. Eventually, though, Alucard is able to defeat Anderson.
As his enemy lays dying before him, Alucard doesn’t taunt him or attempt to humiliate him. Instead, he cries for him while shouting “You’re just like me!” He cries for the man Anderson used to be, for the man that he viewed as his equal and for what he's done himself. As Anderson fades away, he says to Alucard, "Monsters don't cry. And that's why you became one, isn't it? So you wouldn't have to.”
Alucard didn’t become a vampire because he wanted power or immortality. He became a vampire because he was afraid to face his humanity and his God. These are not the fears of a monster. These are the fears of a human. In spite of his propensity towards violence and cruelty, he truly does care for those close to him and he is not quite the monster he believes himself to be. A monster doesn't cry for the man who has tried to kill him repeatedly, because "monsters don't cry." Humans, however, do.