FSF (Free Software Foundation): Richard Stallman’s FSF and GNU are the very beginning and foundation of the modern open source ecosystems and no story of open source could be made without making a mention of them (though he dislikes the term open source vehemently!). On a practical level, Stallman built many tools such as the GNU Compiler (GCC), Emacs editor, build automator (GNU Make), etc. Most Linux distributions heavily depend on several GNU tools that glue the user-land with the kernel. His legacy still continues today in the form of GNOME (GNU Object Manipulation Engine) Project that provides powerful GUI libraries and a modern Desktop to Linux users.
EFF (Electronic Frontier Foundation): They fight for an Open Web and Net Neutrality. In other words, they want the control of Internet to remain in the hands of people like you and me, not the big corporates. If EFF were to stop doing its job, Net Neutrality would have been long since become a joke, but thankfully they are doing their nut and we still have Net Neutrality though the situation isn’t as ideal as it should be. EFF’s recent resignation from W3C in light of W3C’s unwavering insistence on brining DRM and EME standards in web browsers in another example of EFF’s sincerity.
Canonical: Canonical is a company that built an ecosystem around Linux, but focusing on the Desktop world. There was a time in the late 1990s when most programmers dreaded installing Linux on their machines owing to the astronomical time and effort it took to sort their way through partitioning and hardware issues. But Canonical’s Ubuntu operating system changed all that and made installing linux super easy on your PCs. Ubuntu is the reason that many users like myself were able to make the transition from Windows into the Linux world.