The Collaborative International Dictionary of English v.0.48:

Reconciler \Rec"on*ci`ler\ (-s?`l?r), n.
   One who reconciles.
   [1913 Webster]

WordNet (r) 3.0 (2006):

reconciler
    n 1: someone who tries to bring peace [syn: conciliator,
         make-peace, pacifier, peacemaker, reconciler]