Halloween or Hallowe'en, also known as Allhalloween, All Hallows' Eve, or All Saints' Eve, is a celebration observed in a number of countries on 31 October, the eve of the Western Christian feast of All Hallows' Day.
TAYLOR LAUTNER
The actor dressed as Olympic swimmer Ryan Lochte.
PARIS HILTON AND SOFIA RICHIE
The pair posed as Alice in Wonderland and a race car driver.
NINA DOBREV AND LANE CHEEK
The pair dressed as Olympic swimmers Ryan Lochte and Jimmy Feigen.
MARTHA STEWART
The star dressed as Marilyn Monroe.
LILY ALDRIDGE
The model dressed as Audrey Hepburn’s iconic Holly Golightly
KYLIE JENNER
Kylie dressed as Christina Aguilera from her iconic "Dirrty" video.
KOURTNEY KARDASHIAN
The oldest Kardashian sister dressed as a skull demon.
KHLOE KARDASHIAN
Khloe dressed as Carmen San Diego.
KATY PERRY
The singer dressed as a ’50s principal ("Principal Hudson") for her sock hop-themed party.
KATE HUDSON
The actress dressed as a ’50s student for Katy Perry’s sock hop.
HAILEY BALDWIN
The model dressed as a gypsy.
EMILY RATAJKOWSKI
The actress dressed as a modern Cleopatra.
ELLE FANNING
The actress dressed as a fairy.
AMY SCHUMER
The actress dressed as Dustin from Stranger Things.
BETTE MIDLER
The actress dressed as her Hocus Pocus character, Winifred Sanderson.
ALINE WEBER
The model dressed as Leeloo Dallas from The Fifth Element.
ABIGAIL BRESLIN AND NICK LEHMANN
The pair dressed as Harley Quinn and a lumberjack.
JENNA DEWAN TATUM
The actress dressed as a unicorn.
KELLY SAWYER AND JESSICA ALBA
The pair dressed as Patsy and Edina from Absolutely Fabulous.
KATE HUDSON
The actress as a western woman at her Halloween party.
JACOB TREMBLAY
The actor dressed as Marty McFly.
EMMA ROBERTS
The actress dressed as a skull.
NINA DOBREV AND LANE CHEEK
The pair dressed as Leonardo DiCaprio and the horse from The Revenant.
ELIZABETH BANKS
The actress dressed as Mia Wallace and posed with a party-goer dressed as Stranger Things’ Eleven.
HALLE BERRY
The actress dressed as a skeleton.
MARTHA STEWART
Stewart dressed as a zombie nurse.
VANESSA HUDGENS
The actress dressed as a fortune teller.
ALESSANDRA AMBROSIO
The model dressed as Jessica Rabbit.
MARC JACOBS AND CHAR DEFRANCESCO
The pair dressed as body builders Stacie and Larry.
PRESLEY GERBER, KAIA GERBER, RANDE GERBER AND CINDY CRAWFORD
The group dressed as punks.
KENDALL JENNER
Kendall dressed as a goth chick for Kylie’s Halloween dinner party.
The singer dressed as Hillary Clinton for Kate Hudson’s Halloween party.
TYGA AND KYLIE
The couple dressed as skeletons for Kylie’s Dead Dinner.
MARIAH CAREY & NICK CANNON
Carey’s party was a family affair with ex-husband Nick Cannon in costume as Luigi, their son, Moroccan, dressed as Mario and daughter, Monroe, dressed as a Princess. -Harper’s Bazaar