A slang term for an intermediary in a transaction or process chain. A middleman will facilitate interaction between parties, typically for a commission or fee. Some critics say that businesses and customers should try to "cut out the middleman" by dealing directly with each other, avoiding any increased costs or commissions.

In the supply chain, a middleman may represent a distributor who purchases goods from the manufacturer and sells them to a retailer, often at an increased price. Sales people are often considered middlemen, such as real estate agents who match homebuyers with sellers.