Negotiator

to deal or bargain with another or others, as in the preparation of a treaty or contract or in preliminaries to a business deal.

to arrange for or bring about by discussion and settlement of terms

to negotiate a loan.

to manage; transact; conduct

He negotiated an important business deal.

to move through, around, or over in a satisfactory manner: to negotiate a difficult dance step without tripping

to negotiate sharp curves.

to transfer (a draft, promissory note, etc.) to a new owner by endorsement and delivery or by delivery.

noun

adjudicator , ambassador , arbitrator , broker , delegate , diplomat , fixer , go-between * , interagent , intermediary , intermedium , judge , mediator , middleperson , moderator