Halloween costumes are outfits worn on October 31st, the day of Halloween. Halloween is a modern day holiday (spun off of the Gaelic/Druidic/Pagan holiday of All Souls Eve (see Day of the Dead).) Originally a day to remember the dead by celebrating the darker and more gruesome side of human existence, celebrants would dress as their deceased relatives. It has now become a very commercialized celebration. Because of this, popular costumes are often mass manufactured and sold in specialty stores.

What sets Halloween costumes apart from costumes for other celebrations or days of dressing up is that they are often designed to be gruesome or scary. Popular monsters of legend or fiction are regular themes for Halloween costumes, as are pop culture figures like presidents, film or television characters.

Some of the most common and popular Halloween costumes are:

• Ghost
• Vampire
• Frankenstein's Monster
• Witch