How aggressive are gorillas?
Nowadays, people are aware that King Kong was a product of human imagination. However, gorillas do defend themselves with all their (considerable) strength if they feel threatened.
Gorillas are actually rather calm animals, but in certain situations they can become very aggressive and dangerous. The silverback males in particular can cause fatal wounds with their long canines. When two gorilla groups meet, the group leaders often fight; silverbacks have also been known to kill gorilla babies after taking over a gorilla group. Such aggression occurs more frequently with higher population densities (learn more here).
Another situation in which gorilla males attack immediately is when their group is under threat - be it a real threat or a perceived one. For this reason, gorillas need to be habituated to people very slowly, and only when habituated will they accept humans as visitors. When people approach a group, the group leader needs to be 'informed' so as not to surprise him into responding aggressively to the intruders. Hunters in particular have found that encountering a group of gorillas can result in severe injury.