Common quarry and omen-bearing animals of the forest edge, useful for travel scenes, hunting, and signs of disturbance.
Deer are practical campaign animals: meat, hides, antler, tracks, and a reason for people to enter dangerous woods. In winter they also show where forage remains.
Deer and stags appear around the world tree in Norse myth, where harts browse on Yggdrasil. That gives deer a quiet link to the health of the world without making them monsters.
Use deer as a hunting resource, a guide into strange woods, or an early warning when animals flee a place before people understand why.
DM-only encounter details, stat blocks, and running notes are kept at Deer (DM).