Gaming

Not the person you initially asked, but a good one is Eli Whitney's cotton gin that made separating the cotton fiber from the seeds much easier. It had traditionally been done by hand, which is very time consuming. Whitney's invention greatly simplified the process and made cotton farming much more economically viable as an industry, ultimately leading to an extreme expansion in chattel slavery in the Southern United States and serving to solidify a planter aristocracy that would eventually seek to split with the United States in order to create its own slaveholding empire, triggering a Civil War that would decimate a large chunk of the country and kill three quarters of a million people.