The Noghri are a race of bipedal grey-skinned beings that Timothy Zahn created for his Star Wars series.
The Noghri themselves are a quite diminutive race, wiry beings standing barely over a metre high. However, one would be unwise to underestimate them, as they have immense strength and lightning-fast reflexes. They have grey skin (which starts out as a light grey when they are born and gets darker as they get older), large black eyes, and very sharp needle-like teeth.
The Noghri were a relatively primitive race, non-spacefaring, living in clans on their home planet of Honoghr. During the Clone Wars, there was a space battle above Honoghr, which resulted in one of the warring ships to crash, causing massive earthquakes and sending the toxic chemicals it carried to every part of the planet via wind and rain. The chemicals killed off almost all of the plant and animal life.
The survivors gathered in the Clean Land, a section of the land that had been blessedly untouched by the chemicals, and one that had always been a truce ground between the clans. Soon afterwards, Darth Vader and his men landed. A group of Noghri warriors attacked Vader and his men, killing many of them and suffering only a few casualties in return. Only when Vader intervened were the Noghri defeated. Instead of destroying them, however, Vader offered them peace, aid, and the blessing of the Emperor.
The Emperor took advantage of the Noghri's natural fighting skills, and turned them into his private death commandos. The Noghri sent off their young men to fight in the Emperor's wars, in return for aid for their devastated world. Darth Vader later turned the Noghri over to Grand Admiral Thrawn.
In Dark Force Rising, Leia Organa was able to see through the Emperor's and Grand Admiral Thrawn's deception and bring the Noghri to the side of the New Republic. Grand Admiral Thrawn's Noghri bodyguard, Rukh, was the one that assassinated Thrawn during the New Republic's attack on the Bilbringi shipyards.
The Noghri now loyally serve the New Republic, and aim to erase every last remnant of the Empire from the galaxy. More recently, the Noghri have been hiring their services out to smugglers like Talon Karrde.