Software engineers/developers. They come up with software that everyone uses daily. But they work in shitty conditions, get kinda low pay, and because they're not as visible as writers and actors, are not able to hold a strike for kickbacks when their software is used or is still in use.
They basically built the modern world, but are exploited so that the ones who own the company get rich off their backs.
Where do you live? I live in Singapore and am definitely underpaid. Companies hire the cheaper workers from other Asian countries.