This DIY deer costume from Flattery is especially beautiful. The hardest part about this costume is probably making the antlers, which are made out of aluminum foil and paper mache. The body of the costume is made with a brown unitard, some furry fabric, a little felt, and some fabric paint. The most dramatic part of the costume is the deer makeup. You will need a white eye crayon, or white face paint to create the white deer eyes, but otherwise the makeup is pretty standard.
Stop by Flattery for the full and very detailed tutorial.