What is another word for "negotiator"?

Roget's Thesaurus (1911) lists these synonyms for "negotiator": advocate, agent, agree, agreement, ambassador, and, arbitrate, arbitration, arbitrator, attache, attest, attorney, auctioneer, bagman, bailiff, bargain, barter, bond, broker, business, candle, cartel, caveat, charge, charter, clench, clerk, close, come, commercial, commissary, commission, commissionaire, commissioner, committee, compact, complete, completion, compromise, conclude.