Dungeon Master claims that a herd of nineteen unicorns that live in a secret valley whose entrance is hidden behind a waterfall are the last unicorns in the Realm. The herd leader is named Silvermane and is an uncharacteristic bluish-black colour whereas the other unicorns are white.
The horn of a unicorn is called an alicorn and enables the animal to teleport once per day. When Kelek removed the alicorn from a unicorn with sorcery it became grey, enfeebled and incapable of teleporting. It is unknown whether this happens if the alicorn is sawn off or broken off and the above side effects may be a specific to Kelek's sorcery.