copyright troll

Short definition from Wiktionary

Noun

1. 1
   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. 2
   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: 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.