Humandrill

A Humandrill (ヒューマンドリル) is a type of baboon that Roronoa Zoro encountered in Kuraigana Island. They are highly intelligent creatures capable of imitating humans so much that they will mimic any trait they witness. One of the Humandrills even used spit to heal its wounds, which is a folklore remedy. If they were to see peace they would be peaceful creatures; however, seven years ago, they witnessed a war on Kuraigana Island, causing them to learn how to wield weapons and become bloodthirsty warriors.

The Humandrills are very strong: they were a major obstacle to Zoro when he tried to reach the ocean and they eventually destroyed the boat that Juracule Mihawk gave him to leave the island. One of them was seen withstanding Zoro's Oni Giri attack without falling to the ground, using spit to heal its wound. Mihawk reacted with surprise when Zoro revealed that he had defeated them all. Nevertheless, they are afraid of the Shichibukai to the point that they do they not even dare to come near his castle.

Trivia

 * Their name is a combination of the word "human" (which they imitate) and Mandrills, a type of monkey they appear to be.