copyright troll

noun2

1. •
   (disapproving) A person or company that enforces copyrights that it holds for purposes of generating income through strategic litigation, in a manner considered unduly aggressive or opportunistic.
2. •
   (Internet, disapproving) A copyright holder, or agent working on their behalf, who participates in torrents in order to note down and report those unlawfully downloading their copyrighted content.

   • If you join a popular torrent using your own IP address, a copyright troll might make sure you get a sternly-worded threat from your ISP.