Per the DnD5e.info Alignment Guide, a character's alignment is a combination of two factors: their morality and attitude toward society or order. Morality goes from the scope of good to neutral to evil, while attitude toward society and order ranges from lawful, neutral, and chaotic. Further, the guide also defines Chaotic Evil Alignment as those who act with violence while spurned by "greed, hatred, or bloodlust." Does that sound like a familiar vampire lord?
According to Screen Rant, it makes sense why Dracula's DnD alignment is chaotic evil when exploring his core motivations. While other antagonists like Carmillia are plotting for more power or dominance over humanity, Dracula simply abhors humanity enough to destroy it and also himself. The series showed it was humanity that took away his beloved Lisa Tepes and pushed him to his chaotic evil status. And as the Screen Rant article highlights, Alucard described his father's ultimate plan as "the world's longest suicide note."
In addition to his actions, there's another unique link in his alignment thanks to the real-life figure Dracula is based upon. According to the book Dracula, Prince Of Many Faces, Vlad The Impaler was actually a part of a chivalric group known as the Order Of The Dragon. And, as per the Dungeons & Dragons guide, Red Dragons are creatures that often fall under chaotic evil alignment.
Still, that could, of course, just be a mere coincidence.
