intermediator

from WordNet (r) 3.0 (2006)

intermediator
    n 1: a negotiator who acts as a link between parties [syn:
         {mediator}, {go-between}, {intermediator}, {intermediary},
         {intercessor}]

from The Collaborative International Dictionary of English v.0.48

Intermediator \In`ter*me"di*a`tor\, n.
   A mediator.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

29 Moby Thesaurus words for "intermediator":
      agent, connection, deputy, entrepreneur, front, front man,
      go-between, interagent, interceder, intercessor, intermediary,
      intermediate, intermediate agent, intermedium, internuncio,
      intervener, interventionist, interventor, mediator, medium,
      middleman, mouthpiece, negotiant, negotiator, negotiatress,
      negotiatrix, ombudsman, spokesman, spokeswoman