Phantoms

Phantoms is a horror novel by American author Dean Koontz. It takes place in the small Californian mountain town of Snowfield, where doctor Jennifer Paige is taking her younger sister Lisa to live after their mother died of an embolism. It's a picturesque little place, but it doesn't take the sisters long to notice that something's missing--all the people, for starters. They find a few corpses, but most of the town's inhabitants seem to have vanished without a trace. Many of the few bodies they do find obviously died completely terrified, though just how they died isn't immediately evident.

All the phones are down, but eventually they manage to make a call to the Santa Mira sheriff’s office, which sends up a small group of police officers, who in turn summon an army platoon to investigate the possibility of some kind of chemical warfare. What they find is much worse--an ancient creature that can shape shift into whatever it wants, which has come up to the surface of the Earth to feed and which, thanks to its ability to absorb the thoughts of its victims, believes itself to be the devil. If they can’t find a way to kill it, they’re all going to be lunch sooner or later….

It was made into a film starring Peter O'Toole. And Ben Affleck. Who was the bomb in this film.

Phantoms contains examples of:

 * Asshole Victim - Stu Wargle.
 * Beethoven Was an Alien Spy - The Ancient Enemy is apparently responsible for all sorts of real-world historical mass disappearances (including Raleigh’s Lost Colony and the Mayans), and is the direct cause of many satanic/demonic mythos, such as the Greek god Proteus.
 * Big Creepy Crawlies - A giant moth flies in through the window, latches onto a guy, siphons out his brain, and eats his face. All in a matter of seconds. So, next time that Lunesta moth taps at your window, don't let it in. For the love of god.
 * Combat Tentacles - The Ancient Enemy uses one, coated with acid, to decapitate someone.
 * Cruel and Unusual Death - Pretty much everyone who dies.
 * Curiosity Killed the Cast - Especially those not Genre Savvy enough to realize:
 * Darkness Equals Death
 * Eldritch Abomination - The Ancient Enemy.
 * Everybodys Dead Dave - Literally. Everyone.
 * Evil Phone - The Ancient Enemy likes doing this.
 * Five Man Band:
 * The Hero - Sheriff Hammond.
 * The Lancer - Tal Whitman.
 * The Smart Guy (well, gal actually) - Doctor Jennifer Paige.
 * The Big Guy - Gordy Brogan.
 * The Chick - Lisa Paige.
 * Ghost Town - Snowfield.
 * Hell Hotel - It didn’t start out this way, but the Ancient Enemy turned the Candleglow Inn into one.
 * Ironic Nursery Tune - The Ancient Enemy uses a child’s voice to sing ‘Jesus Loves Me’.
 * It Can Think - There’s a nasty Oh Crap moment when the characters realize the Ancient Enemy is deliberately toying with them. It is revealed later that the creature absorbed the knowledge of its victims.
 * No Body Left Behind - Most of the victims are never found--those that are have often been left solely to freak out the living protagonists.
 * Orifice Invasion - Lots of it, in the movie.
 * Redshirt Army - None of the Army CBW division sent to Snowfield survive.
 * Rule of Scary - Sure, the Ancient Enemy is a biological impossibility, but it makes for a great story.
 * Shapeshifting - The Ancient Enemy.
 * Smug Snake - The Ancient Enemy, which believes itself to be a godlike (well, actually Satan-like) entity and commands Timothy Flyte to be its "disciple".
 * Take Our Word for It - Several deaths, particularly of the soldiers, aren't seen -- but they're heard, and the agonized terror of the victims is almost more effective than the deaths we see.
 * The Film of the Book - The movie was a lackluster trimmed version of the novel.
 * Ultimate Evil - The Ancient Enemy. It even thinks it’s Satan.
 * Uncanny Valley - In-universe; some of the shapes the Ancient Enemy creates are considered this by the characters.
 * You Fail Biology Forever - Oh so much, but see Rule of Scary above. It tries to avert this with Biosan (The biological weapon used to kill the monster), which is based on a Real Life organism made by Ananda Chakrabarty to dissolve oil spills.