Trick or treating is most popular in the US, but this frightening group from Australia look very good too:
As we're very fond of a certain emerald island, I found some interesting tidbits from that part of the world:
Halloween is a widely celebrated cultural event in Ireland. It is known in Irish as Oíche Shamhna (Irish pronunciation: [ˈiːhə haunˠə] ee-hah how-nah), literally "Samhain Night". In Irish, Samhain is the name for the month of November. The medieval Irish festival of Samhain marked the end of the harvest, heralding shorter days and the "darker half" of the year. It is linked to the dead revisiting the mortal world, large communal bonfires and associated lore.
Houses are frequently adorned with orange pumpkins, or traditional turnip carved into scary faces; lights or candles are sometimes placed inside the carvings, resulting in an eerie effect. The traditional Halloween cake in Ireland is the barmbrack, which is a fruit bread. The Halloween Brack traditionally contained various objects baked into the bread and was used as a fortune-telling game. In the barmbrack were a pea, a stick, a piece of cloth, a small coin (originally a silver sixpence), and a ring. Each item, when received in the slice, was supposed to carry a meaning to the person concerned: the pea, the person would not marry that year; the stick, "to beat one's wife with", would have an unhappy marriage or continually be in disputes; the cloth or rag, would have bad luck or be poor; the coin, would enjoy good fortune or be rich; and the ring, would be married within the year.
I also found some music related to the theme:
According to legend, "Death" appears at midnight every year on Halloween. Death calls forth the dead from their graves to dance their dance of death for him while he plays his fiddle (here represented by a solo violin). His skeletons dance for him until the rooster crows at dawn, when they must return to their graves until the next year.
In France, La Toussaint is the holiday to celebrate all saints (known and unknown) and the departed, when they take chrysanthemums to the cemeteries. The shops and supermarkets get flooded with large pots of chrysanthemums:
The graves of loved ones look very colourful:
I couldn't leave Mexico out, where El Dia de los Muertos is widely celebrated:
La Catrina (la calavera Catrina) has become the referential image of Death in Mexico, it is common to see her embodied as part of the celebrations of Day of the Dead throughout the country; she has become a motive for the creation of handcrafts made from clay or other materials, her representations may vary, as well as the hat.
La Catrina also appears in a mural by Diego Rivera:
People go to great lengths to look spectacular. This dress is made of paper plates, plastic cups and plastic spoons:
There are many other countries that celebrate death at this time of the year. Every culture had its own way to address the theme, which certainly gives people the opportunity to let their imaginations fly!
I had to add this picture of Halloween in the Kalahari, courtesy of Shapeshifterbelly: