Fiend

Fiend (悪あく魔ま Akuma, "Demon") is a monster Type consisting of cards resembling demons and devils, as well as many other vile, twisted beasts or mischievous beings. Fiends are almost exclusively DARK-Attribute, as there are hundreds of DARK Fiends but only a few of other Attributes. Fiends are one of the most established and powerful Types in the entire Yu-Gi-Oh! franchise. As such, there is no specific Dueling strategy built around them and their play style, although the majority focus on offensive tactics and destroying the opponent's cards, as well as pressuring the opponent by cornering them with stun, lockdown, banishing, and/or milling effects.

Fiends are most notably used by Yami Bakura, Yami Marik, Declan Akaba, Akira Zaizen, and Roa Kirishima. Some of Yami Yugi's, Yugi Muto's, and Jack Atlas' most well-known monsters are Fiends, and Sylvio Sawatari's final Deck is too. Otherwise, Fiends are generally cards used by minor antagonistic characters such as PaniK and Dr. Genome.

Fiend monsters have some Structure Decks of their own: Structure Deck: Devil's Gate/Gates of the Underworld Structure Deck, which focused on "Dark World" monsters, and Structure Deck: Pendulum Domination, which focused on "D/D" monsters.