Beast-Men are a monstrous race found in the roleplaying game Warhammer Fantasy and are based somewhat on legendary creatures such as Minotaurs and Satyrs - originally Beast-Men were part of the Hordes of Chaos but under new rules they eventually received their own Army Book that allowed them to be played as an independent army (much as Ogre Kingdoms established the formerly mercenary-based Ogres as an independent army).
The Beastmen call themselves the "Children as Chaos" and are what is created when the mutating influence of chaos twists beasts into men and men into beasts. The chaos gods own their souls and they are unable to do anything but serve chaos. They tend to be looked-down upon by other chaos gods and the chaos gods themselves who favor servants of other races since they must pledge themselves to chaos willingly while beastmen are devoted to chaos by default. As such, they are outcasts among chaos.
Some scholars believe that Skaven are an offshot of Beast-Men but this is not confirmed and seems somewhat unlikely as Beast-Men seem to gear more towards hooved bestial humanoids rather than the rodent-based Skaven.