When F.W. Murnau made Nosferatu in the ’20s, he had to change the characters’ names and some story details to avoid copyright infringement on Bram Stoker’s Dracula. Even so, the inspiration was undeniable and Stoker’s widow succeeded in obtaining an order for all copies of Nosferatu to be destroyed.
Fortunately, some prints escaped, so by the ’60s the Dracula copyright had expired and the movie began to be circulated again. German director Werner Herzog became a huge fan of the film and decided to remake it. And since Dracula was now in the public domain, he could even use the names of Stoker’s characters.
Still, Herzog’s Nosferatu is a remake of Murnau’s film before it’s an adaptation of Stoker’s novel. Murnau’s plot changes still show up, including Renfield being Harker’s boss, as well as the awesome way that (spoiler!) Dracula is ultimately destroyed. What doesn’t make any sense is that Harker’s wife isn’t called Mina in Herzog’s film, but Lucy. It’s an odd, pointless change.
There’s also an additional twist in the last scene, but that one sounds pretty cool. Unfortunately, I haven’t seen the film yet, but I’m adding it to my list.