Trident

"We grant you power to ruin the world. The power of darkness. Evil spirit of magic trident. You are the King of Darkness."

- Trident Inscription

The Trident is one of Ganon's weapons. He is seen wielding it in A Link to the Past, BS The Legend of Zelda, Ancient Stone Tablets, the Oracle Series, and Four Swords Adventures.

In Four Swords Adventures, the Trident is held in the Pyramid level, and has an inscription nearby. The inscription would mean that the trident is the exact opposite of the Master Sword. The Master sword being the ultimate light weapon while the trident is the ultimate dark weapon. Ganon uses this trident to fire a flurry of bolts, when hit, Link is transported to the Dark World. Secondly when Ganon throws it, the trident leaves a trail of blue fire in its path.

Upon his revival in Oracle of Ages or  Oracle of Seasons, Ganon will be wielding his trident once again, using it to attack in vicious swipes. He also uses this trident to summon energy balls, as do characters such as Phantom Ganon. However, these attacks cannot be deflected.

A Link to the Past
Ganon's Trident makes its first appearance in 'A Link to the Past'', using it in the first stage of his boss battle. He will spin it and toss it at Link while sending fire bats after him. After a certain point, Ganon will abandon this tactic and use his his secret technique of Darkness in lieu of the Trident.

BS The Legend of Zelda and Ancient Stone Tablets
In BS The Legend of Zelda, Ganon fights similarly to how he fought in the original The Legend of Zelda, by turning invisible and shooting fireballs. As such, the Trident is merely cosmetic and not actually used in combat. In Ancient Stone Tablets, he uses it just as he does in A Link to the Past.

Oracle of Ages and Oracle of Seasons
When Ganon is revived in the Oracle of Ages and Oracle of Seasons Password-Linked ending, he uses the Trident to battle Link. He either attacks with a vicious direct swipe or a flurry of energy balls. Most of these attacks can be dodged using the Roc's Feather or Roc's Cape.

Four Swords Adventures
The backstory of the Trident is expanded upon in Four Swords Adventures. Ganondorf found the Trident when he broke Gerudo law and entered the Pyramid across the Desert of Doubt. Inside, he found the Trident underneath an inscription that promised its wielder the power to become the King of Darkness. Ganon uses this Trident during the final battle, where his attacks include throwing the Trident with a trail of blue fire, and shooting a flurry of lightning bolts that send the Links into the Dark World.

Ganon believes that his Trident will grant him the power to destroy the Links, threatening to skewer them on it. Princess Zelda recognizes the Trident and refers to Ganon as the "ancient demon reborn" because he wields it. A Knight of Hyrule mentions that Ganon used the Trident to defeat the Knights and send them into the Dark World.

Trivia

 * Although the Trident did not appear in The Legend of Zelda, official art from the time of A Link to the Past shows Ganon wielding it when he fought Link in that game.
 * Phantom Ganon in Ocarina of Time fights using a similar weapon. Whether it has any connection to Ganon's Trident is unknown.
 * When Midna attacks with the Fused Shadow, she wields a similar pronged weapon.