Reformer /(r?*f?rm"?r)/

Re·form·er

Reformer

n.
  1. One who effects a reformation or amendment; one who labors for, or urges, reform; as, a reformer of manners, or of abuses.
  2. One of those who commenced the reformation of religion in the sixteenth century, as Luther, Melanchthon, Zwingli, and Calvin. (Eccl.Hist.)