Darkness

Darkness is a parallel force to Light in the Kingdom Hearts universe and is also a form of attack from the Kingdom Hearts series. Darkness is associated with evil due to its nature of deception. People may lose their hearts to darkness if they have delved too deep into it. Driven insane by its corruption, they become a Heartless. Those that follow the path of darkness (villains such as Maleficent and Xehanort's Heartless) gain enormous power, but usually lose much of their physical selves to it. Mickey's Keyblade represents darkness, though he follows the path of light.

Darkness can be used for more then just a means of attack and transportation (Corridor of Darkness), as it can also alter the appearance of the user. Ansem and Riku are two users of darkness that can change appearance by utilizing its properties. Riku transformed into Xehanort's Heartless by the power of darkness, while Ansem The Wise used it to become DiZ.

The Dark element is also used as a form of attack by the Heartless, Nobodies, Riku, and some bosses. Sora does not use the darkness as a means of attack, the exception being Anti Form. Sora and his party can be protected from Dark attacks by equipping certain items such as the Midnight Anklet.

However, if a strong hearted person chooses to wield darkness for a greater good Riku while also using the power of light, then they have the skill to dual-wield both elements.