Gem Deer are aggressive Mobs exclusive to Don't Starve Together, introduced in A New Reign. They are equivalents of No-Eyed Deer with a Blue Gem or a Red Gem acting as antlers. When killed, both will drop 2 Meat and 1 Red or Blue Gem depending on the type.
Both types are spawned with Klaus to aid him during the fight after attempting to open the Loot Stash with the Deer Antler. Killing them increases Klaus' strength. If they are still alive when Klaus is defeated they will turn into normal No-Eyed Deer, dropping their corresponding gem.
When approached, Gem Deer will shine their gem to perform a magical attack on the player. The attacks affect the land around the player, giving them a short time to move away before being affected themselves. Each type has different powers.
- The Red Gem type melts the land, which sets lingering players on fire. They are immune to fire-related weapons such as the Fire Staff and Fire Dart. They are vulnerable to freezing weapons such as the Ice Staff.
- The Blue Gem type freezes the land, which freezes lingering players. They are immune to freezing weapons and vulnerable to fire-related weapons.
- From the game's files before the update, their beta appearance's fur from the top of their heads and chest share normal No-Eyed Deer's color being light-brown instead of white. Their collars are also colored in iron rather than golden while lacking bells. This is due to them having temporary "winter" skins.
- While Klaus wasn't spawned, spawning the Gem Deer with debugspawn codes will cause it to permanently change into a normal No-Eyed Deer after few seconds.