The Plague Doctor

The Doctor ( 医者 Isha ), otherwise known as the Plague Doctor, or Doctor for short - Is the Guild master of the Dread Spectre Guild, and the discoverer of the 'Dread Pupil' magic. He utilizes various Black Art spells, including two of which are unique: Susceptione, and Dread Pupil. He found these spells after the destruction of Tartaros' Alegria (Cube), as he salvaged them from the wreckage. Since then, he has all but mastered the techniques and still wishes to expand their powers, and his knowledge of the Darkness- hence forming the Guild 'Dread Spectre'

Appearence
The Doctor generally never reveals his face openly, hence he wears a unique 'Plague Doctor' clothing, with one of the eye-holes tinted red for his singular Dread Pupil. As most of the Dread Spectre members do, he wears a mask to cover his face- this is also a Plague Doctor mask, which is confusing, yet intimidating to his foe.

Non magic abilities
Incredible Strength: Though this could be due to the Dread-Pupils effects on his body (which is still unclear); Doctor has incredibly powerful strength.

Quick reflexes:  Similar to above, Doctors fast reflexes could be from his Dread Pupil, however it is unclear.

Magic abilities
Black Arts: The Doctor is skilled in various types of the black arts, they will be listed below. Death Magic: The Doctor has always had this power acquired, even prior to his discovery of Dread-Pupil and Suscpentione, Death Magic enables the user to kill things with a deadly black miasma.

Living Magic: A form of Magic that brings things to life under the caster's control. Some creations of Zeref, mostly gigantic and powerful demons, have minds of their own, and continue his unknown evil quest. In "The Book of Zeref" it's written how to obtain and use this Magic. The Doctor acquired this from the wreckage of Alegria

Dread-Pupil Magic: Dread Pupil, otherwise known as the Dread Eye; is a form of Black Arts magic that the Doctor acquired after the Wreckage of Alegria,  in which the user casts upon ones self, or a seperate individual giving them an extremely large boost in magic power, agility, strength and endurance- however, the magic comes at a cost: The host's eye (or eyes, varies.) turns almost completely black with a distinct crimson glow for a pupil, as well as black/navy blue veins coursing from either side visibly. It also takes a toll on the users mentality, however 'The Doctor' specifically chooses his members based on intellect and skill.

Suscpentione: Perhaps the most unique and powerful of the three primary Black Arts the Doctor utilizes, Suscpentione is a form of Black Arts magic in which the user casts upon a host, obtaining absolute control over their will and thoughts- however, just as Dread-Pupil- Suscpentione has a toll on the caster. A large, mint-green burn slowly makes its way up the arm by a few milimeters each time it is cast, often leaving the caster in agonising pain. The Doctor still feels this pain, however gas grown used to it- this may be the reason why he wears the Plague Doctor suit.