Heiðrún

Heiðrún, or heidrun, is a unique mob, which spawns only once in the game, in the courtyard of Valhalla. Heiðrún is a goat which functions similar to a mix between cows and sheep: Heiðrún can be right clicked with a bottle to give mead. The goat will eat leaves placed next to it, and will in fact not be able to produce more mead until it has eaten again.