Reapers are the beings that work for Death, and assist spirits in moving on from the mortal realm when they die, maintaining the natural order of life and death. Reapers are typically neutral beings, however a certain segment of them have been known to go "rogue" and offer their various services for a price.
(Not to be confused with Death him/herself or the alien Reapers from the Mass Effect RPG gaming series on xbox/ps3)
They usually keep to the stereotypical appearence of a skeleton figure hidden beneath a black hooded cloak which can be one single long peice of cloth with sleeves, or it can be flowing with many tendrils of fabric mysteriously floating in the air, though this is commonly associated with Death himself (and for argument's sake, it's a dude). The face is actually hidden most of the time as they like sticking to the shadows. Thier main weapons are the Scyth, with some renditions having huge wings - both feathered and bat-like - and some having custom made Scyths, which look more like giant swords.
An example of a reaper would be in the film Ghost Rider, where Johnny Blaze, played by Nicolas Cage, makes a deal with the devil to do his dirty work at night, turning into a skeletal figure clad head to toe in leather. (see picture) Though not working for death, this has the same concept as a Reaper.
In Japanese culture, the shinigami, also known as Death gods for those of you who don't watch Death Note or Blech or some other awesome japanese anime/mangas, are classed as Reapers because of the multitude of numbers.
In Death Note, Ryuk and Rem are Death Gods which start to interfear with the human world by leaving a Death Note book for the mian character to find, called Light. Though they look like a couple of awesome KISS rejects, their purpose is somewhat mitigated by Light's activities.
(For Bleach references, see Shinigami)
