A straw reaper is an agricultural machine used for harvesting grain crops such as wheat, barley, oats, and rice. It performs multiple functions in one operation, including cutting the standing crop, separating the grain from the straw, and then chopping the straw into small pieces.

The basic components of a straw reaper typically include a cutting mechanism (usually a sickle bar or a rotary cutter), a reel to guide the cut crop into the machine, a threshing unit to separate the grain from the straw, and a straw chopper.