What is another word for "propitiator"?

Roget's Thesaurus (1911) lists these synonyms for "propitiator": arbitrate, arbitration, arbitrator, bargain, compromise, consignee, diplomacy, diplomatics, diplomatist, flag, go-between, good, halfway, intercede, intercession, intercessor, interfere, interference, intermeddling, interpose, interposition, intervene, intervention, mediate, mediation, mediatization, mediatize, mediator, mediatorship, mediatory, meet, moderator, negotiate, negotiation, negotiator, offering, parley, peace, peacemaker, person.