Vaati

The villain in the Four Swords subseries of the Zelda games, and the The Legend of Zelda: The Minish Cap. Vaati is a Wind Mage, and is seen taking on two main forms, a humanoid and a monster (much like Ganon and Ganondorf).

In Four Swords
http://zeldad.com/fsa/vato.jpg

Released from his prison within the Four Swords, Vaati kidnaps Princess Zelda, forcing Link to go off and search for the princess.

In Four Swords Adventures
After when Link rescued Zelda and sealed Vaati in Four Swords, Hyrule was at peace until Ganondorf stole the Dark Mirror and created Shadow Link to kidnap Zelda and the Shrine Maidens and trick Link into releasing the Four Sword and releasing Vaati. During Link's adventure to save Hyrule he found out that Vaati is not the real enemy,he found out Ganondorf created Shadow Link to trick Link to release Vaati to distract Link so Ganondorf will steal the Trident to transform into Ganon and take over Hyrule. So Link rescued the Shrine Maidens and Zelda, deafeted Shadow Link with Zelda's help, defeated Vaati and sealed Ganon with the Four Sword with the help of Zelda and the Shrine Maidens, and so peace returns to Hyrule.

In The Minish Cap
http://www.zelda-gc.com/tmc/perso/gufuh_1.jpg

The origin tale of Vaati is told in the adventures that Link faced with the Minish Cap. Originally of the Minish race, Vaati was fascinated by the evil that could come from the heart of man. When his master, Ezlo, fashioned a powerful cap as a gift for the humans, Vaati stole the cap, and transformed his master, so that he would not stop him. Then, taking human form, Vaati set out to find the means to allow him to become the greatest sorcerer the world had ever seen.