Czerka

Czerka is the largest intergalactic company in the Star Wars universe. It's described in detail on it's wookiepedia page, but I've taken the liberty of retrofitting the fictional company for my own uses, and this article details the changes. 
The Company can easily be used with any space age science fiction setting, with some minor changes made. 
Czerka is an intergalactic company that produces pretty much everything. Czerka owns a number of subsidiaries and have branched out in many different directions. At least a third of Czerka's stock is owned by the same holding company and another third is owned by The Commercium. 
Czerka is so big, that they are actually also a corporate nation, owning planets and colonies even, outside of anyone's jurisdiction. As such, CzerkaSec, Czerka's own internal security branch, is actually an established private military force, that Czerka uses to protect it's quasi nations. 
Czerka's history is stained black with corruption and crime, but for the most part, their prices are reasonable, their corporate structure healthy, their employees fairly treated and well paid, and finally their products are at least standard in quality.