Characters who are human, (part of) the main focus, and have an ethnic background other than European (American, Eastern and Western) or East Asian (Japan, Korea, China).
Depiction of Southeastern Asian, Middle Eastern Asian, Hispanic/Latino-Latina, African, and Native American would belong to this pool also. Unless expressed by the content of the image or by the artist themself, characters with dark or tan skin don't necessarily fall into this pool.
