The Satyr are a branch of the Elven Race created by the Magi coruption of Illidan Stormrage.
Following his banishment from Athel Loren he would drift the world for a time, until he came upon the ancient Elven Port of Tail Vena of which he would come to live within. The Elves here would come to worship him as a god, and this adortion would slowly mould them into a new and different race called the Satyr after they undertook a massive ritual which forever changed them. The ritual was Illidan's final fall into darkness as after he changed the thousands of Elves that lived in the port into Satyr there would be no going back, and as he contimplated this moment he was for the first time in a long time convinsed of something without it involving Tyrande when he was persuaded by his commander Xavius. Xavius had been marganalized under the old leadership of the port and thirsted for more power and he saw that Illidan would give him this and for this reason he followed him with extreme loyalty and he was the one that went about convinsing the people to take part in the ritual. The ritual would dramatically change the Elves of the port into an entirely different race called the Satyr and the change was best described by Illidan himself.
"In place of their former sinewy elven bodies, they now possessed massive hairy forms, standing upwards of 9 feet tall. Their hands became claws, their feet replaced by cloven hooves and horns sprouted from their head."
When they changed into the Satyr the High Elves would invade them and just as they were about to fall Illidan Stormrage led the retreat to the fleet where they fled east to the lands of Ind.
Satyrs possess little culture inside the Empire of Outland, but left to their own devices they remain fanatically loyal to Illidan but they gain a unique culture. Their society is loosely hierarchical, and they are organized into groups. Each group is called a "sect". A sect of satyrs lives in the same geographical region and has a specific mission. Satyrs of different sects get along only some of the time. They live in ruins scattered throughout northern Kalimdor and Desolace; satyrs prefer places of corruption to make their homes, such as Felwood and certain areas of Darkshore. Their sects are small, usually no more than a hundred individuals. Satyrs are cruel and sadistic creatures. They enjoy tormenting other creatures, particularly intelligent ones. Satyrs patrol their territory, hoping they can find travelers they can eviscerate in the most bloody manner possible. They operate at a faster level than their former selves — while before they may have been stately and calm, they now burn with feverish energy. Their movements are swift and jagged, like predators sensing prey.