Junk man is the (largely American) term for a person that buys, trades, or collects disparate items (scrap and usable/repairable things) that are considered of little or no value to their owners. This person then tries to sell or trade these items at a profit to other individuals and scrap yards.
The poet Carl Sandburg has a poem called "Junk Man," in which Death is personified by a junk man.[1]