Few plants are completely deer resistant. Deer tend to avoid plants with aromatic foliage, tough leathery or hairy, prickly leaves and plants with milky latex or sap. Variegated Sweet Flag as the foliage is aromatic and there is a Dwarf version of it also. Horsetail Rush, Dwarf Hibiscus, Obedient plant, Cardinal Flower, Pickerel, Blue Flag Iris and Marsh Ferns are supposed to be deer resistant also. I have heard papyrus is deer resistant and Mexican Butterfly Weed.
I was recently asked which bog plants might not be tasty snacks for the deer.