Time for the annual costume cultural appropriation debate to crop up. Some thoughts: Halloween itself is an amalgamation of a number of different cultural practices, which developed (mainly) organically over centuries. One root is in the Gaelic holiday Samhain, which the Celts celebrated as their new year. Another strand is Dia de Muertos in Mexico and Latin America more broadly, which took place at the beginning of summer before the colonial era, when Christianity pushed it to be associated with October 31st. There are other variations throughout the world, on every continent. Transatlantic migration between Europe and the Americas in the 19th century led to a simultaneous spread and consolidation of these varying traditions in those regions. Later, the (largely American based) consumerization of this holiday manifested into what people celebrate today, in terms of dressing up, trick-or-treating, decorating, etc... Ergo, such a holiday formed into a cohesive body by incorporating ideas from many cultures. Halloween itself is a cultural appropriation or amalgamation of many ideas, and no single group can claim it fully. Mocking people without reason is unpleasant to put it mildly, but dressing up in costume and pretending to be something/someone else for one night is not the equivalent of mockery.