The Breakers are a group of telepaths gathered together by Trans Corporation, the agents of the Crimson King. Their sole purpose is to break the Beams holding up the Dark Tower. They were held in Algul Siento until Roland Deschain and his tet freed them, casting them to the Calla.
The Crimson King's goal was to use the Breakers to destroy the Beams, thus destroying the Dark Tower. He would then rule over the Prim with his son, Mordred Deschain.
While they were still Breaking, the leaders of Algul Siento fed them pills which enhanced their abilities. These pills were made from the stolen brain matter from the children of the Callas that the Wolves took from their homes and left them roont.