backgrounder

noun3

1. •
   A briefing or document typically provided prior to a meeting or other event that gives basic details on subjects that are likely to be mentioned.

   • One of the President's aides gave us a ten-minute backgrounder on the dairy industry before the meeting.
2. •
   A person employed to draw backgrounds for a comic or cartoon.

   • […] backgrounders paint static background scenes, and then the animation components are layered on top […] — 1996
3. •
   A cattle farmer or rancher who runs a backgrounding operation.