Westinghouse Electric Company; Westinghouse basically initiated a large portion of the steam industry, which drastically affected each and every one of our lives.
Fun fact, George Westinghouse licensed a patent with Nikola Tesla (after Tesla got screwed over by Edison) for the Alternating Current generator, since Tesla didn't have much money. Long story short, George Westinghouse was probably one of the greatest investors of the century, despite his poor decision to sell his company during a financial and economical crisis.
Tesla then used that Alternating Current generator to power the Chicago World’s Fair, which proved to be a feat for Tesla and his technology.