The Oompa-Loompas are an indigenous people with a rich history. In their native country, Loompaland, they traditionally harvest cacao beans and create architecturally distinct treehouses to escape Snozzwanglers.
Stormtroopers are yet another beautiful ethnic group with an exotic look. Every element of their suit is carefully constructed as a symbolic representation for various elements of their culture and as a reflection of their values and beliefs.
Perhaps the most unique ethnicity in terms of linguistics are the Daleks, who have constructed a beautiful native language which predominantly uses the phrase “EXTERMINATE” as a substitute for almost any word.
A more recent cultural development, the minions are an ethnic group most often celebrated for their unique skin tone. Best known for their intriguing mating calls, minions will often shout “Pa-poi” at one another.
Last but not least, you could always dress up as an Na’vi. They live in traditional tribal societies and have been building up their cultural knowledge for thousands of years.
All these groups have rich histories and cultures that are almost completely irrelevant until they are exploited as trends. Appropriate away!