Link
Introduction
All creatures, big and small, owe their lives to these legendary adventurers. Link's list of accomplishments sprawls longer than we could even begin to list here, but he is most well known for his vital role in keeping Ganon, The King of Evil, safely locked away in the Dark World.
Some of Link's most famous accomplishments include rescuing Princess Zelda on multiple occasions, saving the citizens of Termina from certain demise, as well as freeing the island of Koholint from savage monster attacks. Humble to the last, Link is known not merely as a hero, but as a symbol of courage, strength and wisdom as well. Tales of his bravery will never cease, and his legend will never ever die.
On a side note, Link most likely got his name from the Dutch/German word "links," meaning "left". If you have noticed, Link is left-handed. Another possibility is that he got his name to resemble the "link" between the player and the character.
Links through History
It is common knowledge that throughout the history of Hyrule there have been not only one, but several heroes called Link.
Link I
Link I is the hero seen in Ocarina of Time and Majora's Mask, called the Hero of Time. He was raised in Kokiri Forest, but was not actually a Kokiri. His mother, suffering wounds from a Civil War, found her way to the peaceful forest. Shortly after Link's birth his mother passed away. It was on his tenth birthday that the fairy, Navi, joined him and thus began their quest to save Hyrule. By collecting the three Spiritual Stones, Link I proved himself worthy to wield the Master Sword.
This gave Ganondorf, the Gerudo King, a chance to claim the Triforce. Though his heart was full of greed, he was only able to obtain one piece. The one that suited him the most -- the Triforce of Power. Seven long years, Link I slept in the Chamber of Light. Then using the power of the Seven Sages, later known as the Seven Wise Men, Link I sealed Ganondorf in the Golden Realm, the only place that could contain his power. After this battle, which came to be known as The Imprisoning War, Princess Zelda used her power as a sage to return Link I to his original time. A ten year old once more Link returned the Master Sword to it's pedestal, and departed ways with Navi.
Three months later, Link I, feeling restless again, finds his way to Princess Zelda telling his closest friend of his plans to leave Hyrule. As a reminder of their time in Hyrule together she gives him the Ocarina of Time. Soon after, Link I departs with Epona looking for his companion, Navi. Finding his way into the alternate dimension of Termina, he takes on the task of saving the people of the town from their impending doom. Once again using the Ocarina of Time to travel within a span of three days.
Link II
There is also a new Link (considered the second now that Nintendo announced it's place in the timeline, go to the article to see what i'm talking about) in the not yet released Twilight Princess.
Link III
Link III, as seen in The Wind Waker, is a completely different person. Link III is an island boy from Oustet who spent his life daydreaming. On his tenth birthday his Grandma gives him the Hero Clothes, as the legend of the Hero of Time remains, he is met really only to wear them for that one day. After recieving the clothes, he and his sister, Ayrll, see a merry band of pirates firing a cannon at the giant Helmrock King. The gigantic bird has captured their leader, a young pirate named Tetra. The pirates succesfully manage a direct hit to the Helmrock King, causing the bird to drop Tetra into a small forest on Outset. Link III saves Tetra, but the Helmrock King mistakingly takes Ayrll for Tetra and kidnaps her. Thus beginning Link III's quest. Link who has always dreamed of seeing the world, now actually will. Leaving his family behind and joining the pirates Link III sails off to The Forsaken Fortress. Home of the infamous King of Evil Ganondorf. Who for some unknown reason(perhaps it will be explained in Twilight Princess) is partially free from the seal the Sages in Ocarina of Time placed from him. He is without his magic though, so for a time has been gathering forces and searching for the descedant of Zelda I.
After failing to rescue his sister Link III is flung out to see and left to die by Ganondorf and his minions. However it is by no accident, that a enchanted sail boat, the King of Red Lions finds him. This sail boat gifts link the conducting baton, The Wind Waker, which has the ability to manipulate the winds. Link III finding three pearls of the godesses, is then given the testing ground to prove himself worthy of being a hero. Facing the perils of the Tower of the Gods, Link III proves himself worthy and travels to Hyrule, which is far beneath the waves to draw the Master Sword. Unknown to Link, but the master sword at rest was another part of the seal on Ganondorf. And he now has magic returned. Only then to face Ganondorf and find out that the power of the master sword is no more.
Awakening two sages to return the power to The Master Sword, Link III reforms the Triforce of Courage and is declared the Hero of Winds. Link III then faces Ganondorf with the help of Princess Zelda. Coming right down into his skull with the Master Sword, Ganondorf turns to stone and Hyrule is washed away forever. Leaving the master sword and Ganondorf to sleep at the bottom of an ocean forever. Returning to thier ocean Link III and Tetra/Zelda begin thier quest for the New land that will by Hyrule.
Link IV
Link IV is a direct bloodlink to the Hero of Time, as seen in A Link to the Past and Link's Awakening
Link IV is telepathically contacted to Zelda, who is imprisoned in the castle. Finding three pendants much like the Hero of Time, he finds his way to the Lost Woods, where the Master Sword waits. Using the Master Sword, he travels from Hyrule to the Golden Realm, which had become a twisted, evil place in Ganon's touch. Awakening the seven descendants of the Sages (Seven Wise Men), he uses their power to destroy Ganon.
Link V
Link V is in The Legend of Zelda and The Adventure of Link
There is yet another in the Oracle duo: Oracle of Ages and Oracle of Seasons. A completely different set of characters named Link are the three heroes who have wielded the Four Sword in the three games of the Four Swords series, Four Swords, Four Swords Adventures and The Minish Cap.
Link of the Gorons
The son of Darunia, Link of the Gorons was born sometime during Link, the Hero of Time's seven year long sleep, and named after the hero who saved the Gorons by chasing off the Dodongos, who had taken possession of Dodongo's Cavern, the place that the Gorons used as their chief source of nourishment.