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 within 12 units of the deer, 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.
- Gem Deer were introduced in the Winter's Feast update, alongside the event of the same name.
- During the Winter's Feast event, Gem Deer have a slightly different appearance. Their head and chest fur is silvery white instead of light-brown, also their collars and chains are golden and ornamented with bells rather than colored in iron.
- Spawning the Gem Deer without Klaus using Console Commands will cause them to permanently change into regular No-Eyed Deer after a few seconds.