Is Cosplay Considered Fan Art

A comment from Adam has me thinking: is cosplay really fan art? I have always considered it as much of a valid form of fan art as any other art medium, such as drawing or 3D art. It is just as time consuming as any other form of art, if not more so. Normally it is done out of a love for the series, as other forms of fan art are. So should it be considered fan art, or be separated entirely to a category all of it's own?

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