Trick 'r Treat/Characters

Sam
A strange young trick-or-treater wearing a flour sack mask and orange pyjamas, Sam appears throughout the film without much purpose. He originally appeared in Michael Dougherty's short "Seasons Greetings". However, it becomes clear there's more to Sam than there appears. He is revealed to be, laying the law down on those who break the rules of Halloween (wear a costume, give out candy, never extinguish a jack o'lantern before midnight) with killing intent and revealed to be an Improbable Weapon User and a Killer Rabbit. His fight with Mr. Kreeg reveals him to be, hence why he wears the mask.
 * All Hallow's Eve: What he exists for.
 * Awesome Sack: Sam carries a sack around with him which contains candy and weapons.
 * Beneath the Mask: Sam's face is really
 * Beware the Nice Ones: Sam appears to be a regular innocent trick-or-treater. Guess again.
 * Ceiling Cling: This proves that Sam's
 * Chekhov's Gunman
 * Cool Mask
 * Creepy Child: Oh hell yeah!
 * Did You Just Have Tea With Cthulhu: Steven, Rhonda and Mr. Kreeg to an extent share this trope with him, Steven and Mr. Kreeg giving him candy whilst Rhonda pretty much worships Samhain (the original form of Halloween.)
 * Early-Bird Cameo: Over ten years before the film in the short film Season's Greetings.
 * Fluffy the Terrible
 * Giggling Villain
 * Implacable Man
 * Improbable Weapon User: Sam carries a sack of candy with him...which he uses as weapons. He  with a razor blade in a chocolate bar, and then turns a lollipop into bladed weapon which he uses to
 * Ironic Nursery Tune: "Give me something good to eat..."
 * Kick the Dog: Literally. It's implied he harms Mr. Kreeg's attack dog.
 * Kids Are Cruel: But only if people break or ignore the rules of Halloween.
 * Killer Rabbit: Actually played for laughs in an Easter trailer promoting Fear/Net's future 24 hour marathon of the film.
 * Meaningful Name: Sam is actually short for "Samhain", the Celtic god of death and harvest, and the original form of Halloween. Even more meaningful when he
 * Nigh Invulnerable: He can survive
 * Psychic Powers
 * Room Full of Crazy: Sam decorates Mr. Kreeg's bedroom with a flaming pumpkin, and blood written across the walls and ceilings of the Ironic Nursery Tune.
 * Scary Scarecrow: He's dressed like one.
 * The Reveal:
 * The Speechless: Sam doesn't say a word aside from giggling and screaming.
 * To the Pain: If someone breaks the rules of Halloween.

Shadow Man
A mysterious man shrouded in darkness who stalks Sam in the short Season's Greetings. He follows Sam into an alley way, and appears to beat him up. That is until Sam emerges carrying the man in his sack.
 * Dark Is Evil
 * Fate Worse Than Death: Now that Sam's got his hands on him.

Principal Steven Wilkins
A seemingly innocent school principal who loves Halloween, Steven Wilkins actually hates those who disrespect the customs of Halloween and  He has a son Billy who appears to be molding into his Daddy's Little Villain. He later moonlights as a vampire-like man wearing a hooded cloak, and stalks Laurie. Unfortunately, this doesn't go well when
 * Chekhov's Gun / Fridge Brilliance: The chocolate bar Steven gives Sam is later used to fight Mr. Kreeg.
 * Deadly Prank: Steven poisons Charlie and acts like it was meant to be a Halloween trick.
 * Ironic Echo: Mr. Kreeg says "Screw you!" to Steven when he wishes him happy Halloween. Steven uses this on Mr. Kreeg later, unaware he is being attacked by Sam.
 * Steven also says to Laurie "My my, what big eyes you have" while he's attacking her.
 * Malevolent Masked Man: When he becomes the vampire stalker.
 * Meaningful Background Event: Steven can be seen following Laurie around the celebrations for most of the film.
 * Sadist Teacher: Only to those kids who mistreat Halloween. Charlie gets the worst of his wrath.
 * Serial Killer
 * Vampire Bites Suck: Steven does it for sheer fun.

Billy Wilkins
Daddy's Little Villain, Billy is Steven's loud, but beloved child who loves spending time with his father, particularly on Halloween. He actually shares his father's hatred for rulebreakers, asking him to carve a jack o'lantern,  He also considers Charlie Brown to be an asshole.
 * Cheerful Child: Despite being a lunatic.
 * Creepy Child
 * Like Father, Like Son: Played on when Billy is dressed as his father at the end of the film.
 * Offing the Offspring:

Charlie
A Fat Bastard kid who uses Halloween to cause mischief and steal candy, even though he's diabetic. His attempt to steal candy from Steven's porch results in
 * Asshole Victim
 * The Bully: He's so hated that Sam flips him off in a deleted scene.
 * Fat Bastard
 * Off with His Head
 * Vomit Indiscretion Shot: A combo of blood and chocolate is shot down Steven's front porch by Charlie.

Mr. Kreeg
Steven's neighbour, an aging Jerkass recluse with a Dark and Troubled Past. He has an Angry Guard Dog named Spite (seriously), and arms himself with a shotgun if there's trouble. In the film, Mr. Kreeg hates Halloween and gets an unwelcome visit from Sam, resulting into a Hopeless Boss Fight with the supernatural child. It is revealed that he is  Mr. Kreeg
 * Angry Guard Dog: He has a small dog named Spite.
 * Badass Grandpa: He puts up a good fight against Sam, despite falling down a flight of stairs, and getting glass stuck in his hands.
 * Chekhov's Gun: The chocolate bar Mr. Kreeg puts down before Sam arrives saves his life.
 * Dark and Troubled Past: The reason why he is a shut-in and hates Halloween.
 * The Driver:
 * Hikikomori
 * Hopeless Boss Fight
 * Jerkass
 * Redemption Equals Death
 * Shotguns Are Just Better

The School Bus Kids
Eight disturbed children who were sent to their watery deaths thirty years ago. They are brought back from the dead by Sam to exact their Ghostly Goals on Halloween.
 * Abusive Parents: Their parents paid  to drown their children so they could be free of their burdens.
 * Back From the Dead: Thanks to Macy kicking a jack o'lantern into the lake the bus fell into.
 * Bus Full of Innocents
 * Children Are Innocent: They were before they died.
 * Then again, it is implied that the reason their parents gave up was because they were so twisted/psychotic/deranged/disturbed that nothing could be done to help them.
 * Creepy Child: There are eight undead kids to chose from, and all are wearing their Halloween costumes and desiring flesh.
 * Ghostly Goals: To get revenge on those who wronged them.
 * The Undead

Emma and Henry
A loving couple who have an unpleasant Halloween with their various run-ins with the other characters, plus Emma wearing a bulky robot costume. Returning home, Henry runs inside to watch a sex tape whilst Emma clears up the Halloween decorations before midnight, resulting in Sam paying her a visit and
 * Continuity Cameo: Since she dies at the start of the film, Emma and Henry appear throughout the film.
 * Cruel and Unusual Death: Since Emma is chronologically the last casualty in the film, Sam is so annoyed at this point with rulebreakers that he
 * Dead Star Walking: Emma (Leslie Bibb) dies very early in the film, which is actually the film's ending.
 * Lazy Husband: Apparently he sleeps for half the day, plays video games for the other, and likes watching sex tapes.
 * Robot Girl: Subverted, since she's only wearing a costume.

Laurie
A young, pretty girl Laurie wishes to spend this Halloween trying to have her "first time", accompanied by her older sister Danielle, and two other friends. She spends much of the film wandering around dressed as Little Red Riding Hood until she attacked by Steven. However, she turns the tables on him and reveals she is in fact
 * Anna Paquin
 * Fan Service: Anna Paquin dressed as a nursery rhyme character is likely to attract some people...until the Fan Disservice that occurs later in the film.
 * Hey, It's That Guy!: She's played by Rogue from X-Men.
 * Little Red Riding Hood: She dresses as Little Red Riding Hood in the film.
 * The Reveal: Probably the most surprising of the film.
 * The Schlub Pub Seduction Deduction:
 * Shout-Out: Her name may be a nod to Halloween's Final Girl Laurie Strode.
 * The Schlub Pub Seduction Deduction:
 * Shout-Out: Her name may be a nod to Halloween's Final Girl Laurie Strode.