Malakai (マラカイ, Marakai) is a malevolent entity that is the end result of the Original Demon's energy residue taking on a physical form and gaining its own will as a complete entity. Known and feared as the Will of Hell (意志の地獄, Ishi no Jigoku) by the Demon race, especially the ones residing within Gehenna, it is an entity hellbent on reviving the Original Demon at any cost, causing it to be alternatively known as the Gates of Hades (泉門, Senmon). As a creation of the Original Demon's power, Malakai is an extremely powerful creature, said to even bring a challenge to the likes of the Grand Demon, and is highly feared among its own kin.
According to Malvarak, in the ancient demon language, "Malakai" means "God of Power", reflecting Malakai being an entity literally created from the power of another Demon.
According to the author, Malakai is the second closest thing to Satan within Fairy Tail: Vice.