I should think people would make all kinds of themed costumes, to go with the themed backgrounds. You don't want a robot in Croatoa's fairy woods, for example. Well, not unless you want to show off disparate themes. But judging by the OP's comments, they're looking for
<picture of horror backdrop> + <classic horror style characters>
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<picture of space> + <classic retro or futuristic spacey characters>
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<picture of modern street> + <modern characters>
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<picture of destroyed city> + <"Fallout" style characters>
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<picture of woods> + <fantasy characters>
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<picture of boiling magma> + <demonic characters>
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etc etc etc etc