Animal Species/Other

Horn Eaters
Horn Eaters (ツノクイ, Tsuno Kui) are a type of creature featured prominently in the third One Piece movie. They are large herbivorous armadillo-like rhinos. They are used by Count Butler to herd the various other horned animals on Crown Island in order to chop their horns off.

Unseen
Water Buffalo: Though none are seen in the series, a zombie has a buffalo's head. Also, one of the Whitebeard Pirates's division commanders named Atmos, is known by his epihlet "Water Buffalo Atmos".