Alucard works with the Hellsing Organization against other vampires and evil forces. He fights with ferocity and often extreme cruelty, rarely killing until his target has been disabled and humiliated, while frequently allowing enemies more than one chance to kill him.
As revealed in volume 8 of the manga, he is Count Dracula (Alucard is Dracula spelled backwards). Soon after the events presented in Bram Stoker's original novel, Dracula was defeated by Abraham Van Helsing and became the family's loyal servant. Decades later, Abraham's descendant Arthur Hellsing gives the Count his current name: "Alucard". The manga is set over a hundred years later, where the Hellsing Organization is forced to fight the remnants of a Nazi battalion.
He typically dresses in a distinctive Victorian and western fashion, with a charcoal suit, leather riding boots, a red cravat, and a long red duster (resembling Van Helsing's duster). He also wears a red fedora with a wide, floppy brim and a pair of circular, wire-framed sunglasses (which are similar in design to glacier sunglasses). However, this form seems to be a part of his being as he can change it at will. (Information used from wikipedia)