Monkey
Monkeys are recurring bit part players in Zelda games. They are often mischievious and skittish, but come through in a pinch. They typically resemble chimpanzees, macaques or other small "new world" monkeys. Most are not enemies, but either help or are helped by Link.
A Link to the Past
A Rupee-loving chimpanzee named Kiki appears in A Link to the Past, shortly before Link ventures into the Palace of Darkness. He asks the young hero for 10 rupees, after which he will follow Link.
Link's Awakening
At Toronbo Shores, a monkey throws coconuts and bombs at Link. He is an enemy, and can be jostled out of the tree with the Pegasus Boots.
Southeast of Kanalet Castle is a friendly (but confused) monkey also named Kiki[1], standing in front of the moat. Kiki plays an important part in the trading sequence.
Majora's Mask
This monkey can be found in the Woods of Mystery. He guides Link through the passages and finally to the injured witch Koume, whom Link has to heal with a red potion from Kotake.
After helping Koume, three monkeys approach Link upon exiting the Woods of Mystery. They ask Link to rescue their brother from the Deku Palace, where he is being locked up for kidnapping the Deku Princess. With the help of a Magic Bean, Link can reach the falsely accused monkey by flying across the palace's walls as Deku Link. The monkey teaches Link the Sonata of Awakening, which grants him access into the Woodfall Temple.
After rescuing the Deku Princess, Link brings her back to the Deku King. The monkey is set loose and thanks Link for his brave efforts.
Oracle of Ages
Several monkeys appear in the Forest of Time among several other animals. Many of the monkeys tell Link: "We are going to build paradise."
Twilight Princess
Monkeys play a very important role in the first dungeon of Twilight Princess. Seven monkeys are captured at various points within, and Link must set them free to progress. In return, the monkeys assist the hero by climbing on ropes and swinging him to far away platforms.
Once four monkeys are set free, they will lead Link to their leader, a large baboon called Ook. He has been turned evil by a parasitic arachnid (possibly from the Twilight) and throws the Gale Boomerang at Link from columns situated around the room. If Link rolls into the columns, he can knock Ook off, making him vulnerable. Once defeated, Ook loses his parasite, and drops the Gale Boomerang for Link to pick up. Later, Ook helps Link defeat the Diababa by swinging back and forth with a Bombling in his grip, allowing Link to use the boomerang to blow it into the boss.
Monkeys are seen in a few other places in Faron Woods, either in need of help or willing to help Link in his quest. They appear to be intelligent and friendly towards humans.
Tingle's Love Balloon Trip
A monkey know as Masaru appears in Color Changing Tingle's Love Balloon Trip. Tingle can use bananas to lure him down from a tree. He also will temporarily accompany Tingle on his quest.