I'd say since Bela Lugosi played Dracula as an elegant gentleman, the sexy vampire trope was born, but it is a relative new development.
Hehe since this is now also The Vampyre thread - worth noting that Lord Ruthven predates Stoker's Dracula by 3 generations, and Bela's 'gentleman Dracula' performance by more than a century. The suggestion has long been that Lord Ruthven was modelled on Lord Byron as the ultimate predatory gentleman chasing skirts, since Polidori was Byron's travelling companion and saw how dude operated when shades were drawn.
The legend of Vampyre's drafting is quite famous - as a parlour game challenge. The other celebrated story to come out of it was Mary Shelly's Frankenstien. So they are forever linked, well before cinema was invented. Also sexualized, pretty thoroughly in both camps before the screen was made silver. Le Fanu's Carmilla, the lesbian vampire archetype, is earlier than Stoker's Dracula too. Max Schreck's Nosferatu painted Count Orlok as a vamp ghoul in his knockoff rendition, but the gentleman version is the earlier incarnation. It was already well established in theater by the time Bram Stoker came along, and used the baked-in theme for his own gothic romance riff.
Coppola's film adaptation is pretty brilliant. Almost all the special effects were shot in-camera, which is what makes it such a masterpiece of traditional filmaking (along with the score! Obviously hehe) but also because he treated the source material with a fairly deft hand, understanding pretty well what Stoker was ripping off and updating, and the general milleau that he was borrowing from. He definitely didn't invent it though, and it wasn't exactly novel at the time it debuted. But the cinema eclipsed everything as soon as it arrived, and so Bela did pretty much conquer the world with his performance and seared it into the collective conciousness forevermore. Anne Rice did something rather similar, which is why she's so beloved. Even the tween vampires hit pretty close to the mark there, though I generally dislike that aesthetic.
Schreck still deserves some serious love though as the dominant counterbalancing visual archetype. His shadowplay performance was so memorable and iconic that it remains a hallmark of the genre, even if the general public hasn't watched silent films in nearly 100 years. Like Lang's Metropolis, clips from Nosferatu endure as legendary. Even if we've never seen it, we'd still know it, cause the reach is just that long- with those creepy fingers! Genius, always!
Where exactly Astarion fits in that legacy, a little bit harder for me to parse heheh
