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. 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: one of them was able to withstand the Oni Giri attack from Zoro without falling to the ground; they were an major obstacle to Zoro when he tried to reach the ocean; and Juracule Mihawk reacted with surprise when Zoro reveals that he defeated them all. Nevertheless, they are afraid of Mihawk 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.