Nouns

(n)jobber, middleman, wholesalersomeone who buys large quantities of goods and resells to merchants rather than to the ultimate customers
(n)interlocutor, middlemanthe performer in the middle of a minstrel line who engages the others in talk
(n)contact, middlemana person who is in a position to give you special assistance“he used his business contacts to get an introduction to the governor”