The Brain Trust was a group of six incredibly powerful telepaths bred by Sinister without bodies to psionically anesthetize the Breeding Pens. They acted as an inhibitors, breaking the will of the prisoners as the cause of their lack of will to even try and break free.

They were destroyed by Jean Grey during her escape from the pens with Cyclops. This led to the rioting and revolution of the prisoners inside of the Breeding Pens.