Kruk is a monkey that is the head of the Ninja Monkey Guards of Marim, and is located on the east side of the gate, up on the hill. He is the monkey that shouts for the gates to be opened when you approach in monkey form. He is involved in the Monkey Madness quest, and players must talk to him before meeting King Awowogei to make an alliance with him. Although he has a combat level, he cannot be attacked, nor does he directly attack the player (he simply knocks the player unconscious and sends them to jail instead if they are not wearing a Greegree).
He is slightly bigger than the other monkey ninjas. If you are knocked unconscious by him, you will be sent to the jail. To reach him, go around to the back of the cliff on the west side of the bamboo gate and go up the path. Climb the ladder at the top of the cliff, cross the bridge and go down the other ladder.