Ass Pull: One of the most famous in movie history; F. W. Murnau couldn't figure out how to kill Orlock, so he finally just said "Uh, sunlight? Yeah, that works..." Since then, every vampire in fiction has been vulnerable to it. Incidentally, the effect can also utterly fail if you see the silent film in a version without the tints, since in plain black-and-white, the orthochromatic film stock doesn't distinguish between day and night, and the tints (dark blue for night, amber for day) do the job better to distinguish both.
Nosferatu wasn't the first adaptation of Dracula; a now-lost Hungarian film, Karoly Lajthay's Dracula's Death, came out a year earlier. From surviving descriptions, Lajthay took far greater liberties with the source material than Murnau.
Max Schreck was a prolific stage and screen actor; Nosferatu was far from his only role, though it's certainly his most well-known today. This myth remains strangely persistent even in the Internet era, where Schreck's background is easily researchable, to the point where some writers have posited a Conspiracy Theory that Murnau falsely credited Schreck in place of an unknown actor. It's unclear how the rumor started, though it may be because of Schreck's eccentric personality (he was reportedly a loner with a bizarre, unsettling sense of humor), a joke by a Greek film historian that Murnau must have cast a real vampire as Orlok,note which inspired the film Shadow of the Vampire or perhaps his performance is just that good.
Complete Monster: Count Orlok, the eponymous "Nosferatu," is one of the earliest examples of vampires in cinema and one of the most terrifying. When Thomas Hutter arrives in the Transylvanian Carpathian Mountains, the locals speak Orlok's name in hushed whispers and don't dare to venture out at dark. Upon meeting Orlok, Hutter is attacked and the count tries to feed from him fatally before being repulsed. Hutter witnesses Orlok loading up several coffins to be transported across the sea, and Orlok later kills the crew of the schooner transporting him. The other coffins are revealed to also contain plague-bearing rats, and Orlok's arrival spreads a deathly plague all over Europe. He uses the plague as cover to feed on the people of Hutter's home village of Wisborg without suspicion before Hutter's innocent wife Ellen catches his eye. Orlok attacks Ellen, draining her to death in her Heroic Sacrifice to keep him distracted before the sun rises to destroy him. Orlok had spawned a legion of imitators and while later vampires were portrayed as sophisticated, urbane and charming, Orlok is nothing more than a cunning, evil and ravenous beast that can barely pass as a human being.
The scene where Hutter/Harker and Orlok/Dracula are commiserating together before Orlok is revealed to be a vampire comes across as kind of hilarious given how incredibly obvious it is that the guy is clearly an inhuman monster who reacts very suspiciously to the sight of blood, yet Hutter never seems to think too hard on it until it's spelled out for him.
In the opening scenes the villagers claim that a werewolf roams through the forest at night. The atmosphere is really creepy and the audience wonders what this creature will look like. When the protagonist goes to sleep, the camera shows a wolflike creature walking in the forest, but it falls flat on its face due to having the "werewolf" be played by a striped hyena.
The "plague rats" might have been frightening if they weren't obviously pet rats.
Signature Scene: The plague ship massacre especially the final part where Orlock comes on deck and stands in an empty ship all alone after killing all the crew.
The awakening and rising of Count Orlock from his casket, which has constantly been stated as one of the greatest and most terrifying moments in cinematic horror.
Visual Effects of Awesome: Max Schreck looks absolutely phenomenal in his Count Orlok attire, genuinely looking like a hideous monster of the night. Especially impressive for the time it was produced. Part of the reason it worked is because of the greater realism. It's often neglected that this poster-child of German Expressionism made extensive use of location shooting.
As well as Richard Wagner's Rheingold, used when darkness falls during Harker's walk to the castle, culminating in him (and the audience) seeing the vampire for the first time.
Narm: In Mexico the intro scene with the mummies was rendered completely ineffective as most viewers in the country recognized they are the famous Momias de Guanajuato. Yes, the same ones El Santo fought that one time.