Deconstruction: Not only is it the Ur Example of the zombie apocalypse, but it also deconstructs the notion of the last human survivors. In this world, the monsters have become the norm, and the last human is simply a relic of the past.
Doing in the Wizard : The mythological traits of vampirism are all defined as either caused by the vampirus bacillum, or as a psychological reaction to the infected's realizing they've become a creature out of a pulp novel. On one occasion, Neville observes a vampire climbing a lamppost and jumping off, and presumes that the individual believed itself to be able to turn into a bat.
Downer Ending: Neville, due to killing partial vampires, is about to be executed. The spy he fell in love with gives him a suicide pill to end his misery.
The Dreaded: Neville is this to the Vampires. Even when captured, many are terrified just by the sight of him.
Flashbacks: This time showing how his wife succumbed to the infection, and forced to drive to a government bonfire to burn his dead daughter.
Heel Realisation: A rather poignant one in the ending, as Neville realizes, with horror, why the people who came after him are about to execute them - he was killing vampires who were beginning to stave off the worst urges, and thus terrified the survivors - and civilization's last hope.
He Who Fights Monsters: Neville eventually discovers that some of the infected people have discovered a means of suppressing more dangerous effects of the vampire bacteria, and that many of the vampires he's been killing during his daytime hunts were innocent people. He's pretty much their monster of legend, thus the title.
Immune to Bullets: The dead vampires (ones not infected while alive) have this, due to their wounds healing instantaneously, whereas stakes (and other impalings) keep the wound open.
Neon Sign Hideout: Played for drama for a change. Every vampire in LA knows where the last normal human in the city lives, so each dusk the vampires start flocking around Neville's house.
Ominous Latin Chanting: Ominous classical music more like. Look up the full names to the music Neville plays to keep his mind off the vampires; Sc÷nberg Transfigured Night, The Year of the Plague, Bernstein Symphony No. 2 (The Age of Anxiety), Schubert Symphony No. 4 (Tragic)... Emphasis on ominous, as he uses the music to drown out the hell the vampires break loose outside his house every night.
The Only One Allowed to Defeat You: Neville seems to adopt this stance towards his vampirised neighbor, even if there isn't anyone else out there to defeat him. When the partial vampires get to him first, Neville naturally doesn't take it very well.
Our Vampires Are Different: It's stated the vampires are dumb. Not zombie-dumb, but still idiots, running on instinct alone. Ben Cortman is an exception to this, and Neville latches on to finding out why to keep him sane. He finds:
There are two distinct variations: those infected when alive, and those infected post-mortem.
Almost all of the traditional wards against vampires are apparently psychological. Garlic may or may not be a sort of anti-placebo effect, though Neville notices vampires coughing and choking whenever they're hit with garlic powder. Neville further hypothesizes things like the cross and mirror to be a result of extreme self-loathing. The cross has no effect on his Jewish neighbor, but as soon as he gets out the Star of David and a Torah, Ben begins panicking and doing everything he can to get away from the symbols.
The vampires may be believing their own pop culture. Neville witnesses one vampire leap off from a street light and hypothesizes he was trying to turn into a bat.
Vampirism is caused by bacteria, and infects the living and dead. Living vampires are vulnerable to everything a human is vulnerable to, but dead vampires' lack of a heartbeat causes a vacuum that seals off any wound that isn't large (such as small arms fire). Hence why stakes are so effective: they force the wound open and bypasses the vampire's regeneration.
Dead vampires crumble into dust when staked. Neville remembers talking to a black gravekeeper who talked about vacuum-preserved corpses - any introduction of air would cause the corpses to crumble into dust.
Sanity Slippage: Neville gets dangerously close to tossing himself to the vampires several times.
Staking the Loved One: In the book, Neville has to do this to his wife after she had already died from the plague and he buried her body because he couldn't bear to burn her like he had to do to his daughter. She then comes back as a vampire trying to kill him and he has to kill her all over again, this time presumably by staking
There Is Another: Subverted. When Ruth comes along, it appears that Neville might not be the only unaffected person still alive...And then it turns out that Ruth is The Mole for the partial vampires sent to spy on his defenses. Any and all survivors succumbed to the disease, and only stave it off by way of medicine.
Took a Level in Badass: After a modest Time Skip, Neville goes from being a normal guy who happens to be immune to the vampire bacteria and copes with alcohol to a muscled vampire-slaying beard-toting badass. in that time he's killed numerous partial vampires and figured out their weaknesses and origin. Though his social skills have gone out the window from so many years of not talking to anyone. He also starts going Jack Bauer on his neighbor, what with the chair and the Torah.
Van Helsing Hate Crimes: Turns out Neville has been killing partially-infected vampires alongside fully-infected ones, and is hunted down and executed for this. Oops.
Yank the Dog's Chain: When he comes across an apparently unaffected dog out in the sun, Neville practically gets taken over with Cuteness Proximity as he plans to win over the thing and keep it as a pet. It doesn't end well.