A nerf is a fictional alien animal featured in the Star Wars multimedia franchise. They were first referenced in the 1980 film Star Wars Episode V: The Empire Strikes Back, when Leia Organa insultingly called Han Solo a "nerf herder".
Nerfs are large bovine-like creatures with thick, furry coats and large horns. By Earth standards, they are the equivalent of cows. One who is tasked with overseeing and providing for nerfs is called a nerf herder. The species originated on the planet Alderaan, but have also been relocated to nerf farms on other worlds.