The Far-Outsiders is the cryptic code-name given by the Chiss who inhabit the edges of the galaxy, for the extra-galactic alien force that began assailing the Unknown Regions in the years during the Galactic Civil War. It is likely that these are actually the Yuuzhan Vong, who launched a siege on the galaxy from year 25-30 ABY.
The name "Far-Outsiders" is also used by the inhabitants of Zonama Sekot to describe the invaders that attacked their planet. The Far-Outsiders are referred to in the singular, but the Chiss named Stent once told Jedi Mara Jade that there were "a hundred different threats out there that would freeze your blood if you knew about them. The Ruling Families can't stop them; neither can any power in the region.", suggesting that the term "The Far-Outsiders" may apply to any unknown hostile race originating from outside the galaxy.