Ganon was an evil wizard who sought to conquer the world of Hyrule, and who possessed the Triforce of Power. He was stopped time and time again by Link and Zelda, Princess, who finally vanquished him- or so they thought. Instead, he was severely weakened.
To regain his might, Ganon aligned with Mother Brain, who managed to acquire the Potion of Power for him. However, once he was restored to his full power, he (predictably) turned on Mother Brain and attempted to destroy Link, Zelda, and the N-Team. However, a magically enhanced shield reflected the wizard's power back at him, and seemingly destroyed him- for good.