Okay, you're asking about Dio, and honestly, this feels like it depends entirely on which corner of the internet you live in. For a whole lot of people, the immediate, heart-stopping association is Dio Brando from 'JoJo's Bizarre Adventure'. He's not from a novel, but a manga and anime, and his influence is so huge he bleeds into the novel-sphere.
He's the archetype of the charismatic, petty, and utterly irredeemable villain. The kind of character who starts as a jealous, class-warfare-driven street rat and evolves—or devolves—into a centuries-old vampire and ultimate evil. His role is the benchmark for a villain who steals every scene he's in, who is genuinely terrifying but also magnetically watchable. He's less a character you love to hate and more one you hate to love, you know? His presence defines the hero's journey for generations of the Joestar family.
Reading web novels now, especially in the regressor or system genres, you see so many 'final bosses' that are just pale imitations of that Dio energy—all the flamboyant cruelty without the foundational pettiness that makes him uniquely compelling. He set the bar.