proscriber

noun

1. One who, or that which, proscribes, denounces, or prohibits.

   “In a period of quiet, he had acquired the name of a man of worth; in darker days, he left the renown of a pitiless proscriber.”

   ““In principle,” he declared, “proscription is not only a crime, but a fault; history is full of instances, showing how proscribers have in their turn been forced into the ranks of the proscribed."”

   “I made no connection to the fact that the other proscribers of books were Hitler and the Catholic Church.”