Girallon

Girallon somewhat resemble ferociously large ape like creatures. However, their most obvious defining feature is that they possess four arms instead of the typical two found on other ape species. 
Girallon's are more intelligent than other primates. It is believed that they are the result of magical manipulations of apes to make a more capable and terrifying creature that would be useful for guarding important locations. 
Whatever the origins of these beasts, many now roam freely through the jungles of Chult. Their mercurial temperaments make them an unpredictable and dangerous encounter for any explorers.