Mask

Masks are recurring items in the Legend of Zelda series. Masks usually have different properties that are activated when Link wears one. However, in The Legend of Zelda: Ocarina of Time, the Goron, Gerudo, and Zora masks have no active function at all; they simply look amusing. Other masks may also be exclusively used in specific portions of the respective games.

The Legend of Zelda: Ocarina of Time
There is a side quest Link can complete to obtain the Mask of Truth. Once the Happy Mask Shop in Hyrule Castle Town opens, Link can borrow a mask from the shop, so as to sell it to someone else and return the money to the Happy Mask Salesman. Once Link manages to sell four of the masks, he is given the Mask of Truth, as well as three other masks that do nothing.

Masks

 * Keaton Mask
 * Skull Mask
 * Spooky Mask
 * Bunny Hood
 * Mask of Truth
 * Goron Mask
 * Gerudo Mask
 * Zora Mask

The Legend of Zelda: Majora's Mask
Masks are an essential part of Majora's Mask. Other than the eponymous Majora's Mask, there are 24 masks that Link can collect by performing various tasks. When Link has received 23, he can give them to the Lunar Children on the Moon in exchange for the Fierce Deity's Mask, the final 24th mask. In addition to these 24 masks, there are also four special masks known as Boss Remains, each one resembling one of the game's four bosses. Link needs to collect these masks in order to free the Four Giants sealed inside the masks. Finally, there are some masks that play a part in the story, but cannot be used in any capacity, as well as the many masks found on the backpack of the Happy Mask Salesman.

Masks

 * All-Night Mask
 * Blast Mask
 * Boss Remains
 * Bremen Mask
 * Bunny Hood
 * Captain's Hat
 * Circus Leader's Mask
 * Couple's Mask
 * Deku Mask
 * Don Gero's Mask
 * Fierce Deity's Mask
 * Garo's Mask
 * Giant's Mask
 * Gibdo Mask
 * Goron Mask
 * Great Fairy Mask
 * Kafei's Mask
 * Kamaro Mask
 * Keaton Mask
 * Mask of Scents
 * Mask of Truth
 * Moon Mask
 * Postman's Hat
 * Romani's Mask
 * Stone Mask
 * Sun Mask
 * Zora Mask

The Legend of Zelda: Oracle of Ages
The Doggie Mask is part of the trading quest for the Noble Sword. If Link trades a Tasty Meat to the Happy Mask Salesman, he receives this mask. Link then can trade it with Mamamu Yan for a Dumbbell.

The Legend of Zelda: The Wind Waker
The Hero's Charm allows Link to see an enemy's health.

Also, in the Nintendo Gallery in Forest Haven, on the wall behind Carlov the Sculptor, can be seen the Bunny Hood, the Goron Mask, the Keaton mask, and a fourth mask that looks very similar to the All-Night Mask.

The Legend of Zelda: Twilight Princess
The Hawkeye increases visual acuity, and can be used in conjunction with the Bow to create a "sniper scope." Interestingly, it is never shown on Link's head at any point in the game, althought it is assumed that he has it on.