Zelda: Zelda appears in almost every Zelda game. she is the princess of Hyrule, and the bearer of the Trifroce of Wisdom in many games. In the first Legend of Zelda game's instruction booklet, it says (or implies) that she is Link's sister, but in other games it doesnot appear that that way.

Ganondorf:The main villain in the series (with Vaati as the second), he too posses a peice of the triforce. Ganondorf controls the Triforce of Power. Ganondorf has another form known as Ganon which is created by his rage and the strength of the Triforce of Power.

 

Ganondorf is the leader of the Gerudo Theives. He is the only male in the tribe, and in Ocarina of Time his surrogate (adoptive) mothers are the Twin Witches Koume  and Kotake.

 

Link: The hero of the series, he is the bearer of the Triforce of Courage and is in every game. Link is nomally accompanied by a 'sidekick' such as a Fairy or a magical cap.

 

Link has taken many forms, as he is not always the same between games. You play as a reincarnation/descendant of Link in Wind Waker. Link is almost always referred to as the Hero of Time. Link starts out at different ages in different games (he is an orpaned boy living with the Kokiri in OOT, but a young adult in Link's Awakening.)