thought police

noun

a group of people with totalitarian views on a given subject, who constantly monitor others for any deviation from prescribed thinking

Word Origin for thought police

C20: from the Thought Police described by George Orwell in his novel Nineteen Eighty-Four (1949)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012