Isengarder

A traitor to the White Council, Saruman began building an army at Isengard. Around the year 2990 of the Third Age, he drew some of the Northern Orcs of the Misty Mountains into his service, keeping them in pits of mud carved out beneath Isengard.

It is said that Saruman may have used these Orcs for purposes of "special breeding" in many experiments. Some of these experiments were influenced by the methods of Morgoth and Sauron and involved cross-breeding Orcs with Men, creating many different breeds of Isengarders, such as the vile and cunning Half-orcs and the powerful Uruk-hai.