..or more specifically Gibbons, Gorillas and Chimpanzees.
The Gorilla and the Chimpanzee are a part of the family of great apes which also includes Humans. Both of these apes are very powerful animals with complex social behaviors. Of the two species the gorilla is much strong but it is the chimpanzee that is more dangerous. Chimps can become very aggressive and will kill other chimps, humans or other animals. They also have displayed a very high intelligence and willing ability to use simple tools.
Read more on the Red Ash Chimps and Gorillas.
The Gibbon is one of the largest members of the Lesser Apes. It is well know for its close family structures around a pair-boned alpha male and female. The others in a group are children and sub-adults. While these apes may not offer the level of danger a chimp or gorilla can they can make for a good plot device as gibbons are also very alert to their territory and will make loud vocalizations when an intruder is spotted, not a good thing for players trying to evade notice.
Read more on the Red Ash Gibbons.
All the Best,