What does it mean when you see the reaper in your dreams?

Without more details it is hard to come to a more personalized answer, but in general it is an amazingly dynamic and creative kind of dream. Negative associations with death are merely obvious, not central. In dreams the Grim Reaper is more an invitation to take account, and to become energized (not frightened) by possibilities. There is even a sense, creatively speaking, of the dreamer wanting to devour good things-- which, when you think about it, is something that the Grim Reaper does! Have no fear. Jump into something good and devour it for all it's worth.