The Stalhorse in Zelda Tears of the Kingdom is a special type of horse. It is basically the skeleton of a horse that only spawns at night. If it spawns during the day, its bones dissemble and break apart, resulting in death. These horses are special as they allow their riders to travel in Gloom-infected areas without taking any damage.
You cannot tame the Stalhorse as the stable owners view it as a monster and fear that it may harm the other animals. You can never find the Stalhorse alone in Zelda TotK. A Stalkoblin, Mokoblin, or Bokoblin Rider always accompanies it.
Where to find Stalhorse in Zelda TotK
You can find Stalhorses in the Sanidin Park ruins during the side quest. Or they can be easily found in the Depths due to the dark environment.
Stalhorse location in the Sanidin Park Ruins
There is one catch to finding this creature. You must complete the “Horse Guard’s Request” side quest in Zelda Tears of the Kingdom. You can get this quest from any nearby stable. All you need to do is talk to Toffa at the stable. He will provide you with a hint of the Sanidin Ruins.
Travel to the location and tame the Stalhorse. Bring it back to Toffa, and he will reward you with A Purple Rupee (equivalent to 50 Rupees). This side quest will unlock Sanidin Ruins on your map, and you can also see and interact with the Zelda TotK Stalhorses now.
The map given above can be used as a reference point, or you can follow these coordinates; -1645, -0684 and 0136
Stalhorse location in The Depths of Hyrule
You can also find the Stalhorses in the Depths of Hyrule. They are found abundantly in this region due to the dark environment.
For example, you can find Stalhorses by traveling to the Nisoij Lightroot in Zelda Tears of the Kingdom. Take the Great Hyrule Field Chasm, the nearest one to this Lightroot. You can find a couple of Stalhorses next to a campfire.