Etherious

Etherious are a race of Demons that were born from the Books of Zeref. They are one of the main villains in Fairy Tail.

Info
Etherious is the given name to the subspecies of the Demon race that were created from the books made by the Dark Mage Zeref. Unlike the Demons that inhabit Galuna Island, not all Etherious possess wings and they do not all possess Human forms. Also, in stark contrast to the rest of the living organisms capable of doing so, Etherious, or at least Tartarus Etherious in particular, do not make use of Magic, but rather Curses, which accordingly run off of Curse Power. Also, various members of the Etherious subspecies have displayed the ability to enter a so-called Etherious Form, in which their appearances change and they gain access to an enhanced set of their already available abilities, something which is dubbed as utilizing the "real power" of the race. Some members, however, have displayed the ability to enter a form with power comparable to that of the Etherious Form, but of a different nature; such members include Ezel, who dons armor and turns his limbs into actual swords in a process that he refers to as "Slash Attack Mode", and Sayla, who increases her power by removing her own personal "limiter" via her Curse, Macro.