Ancient Marshall D. Teach

Ancient Marshall D. Teach commonly referred to as Blackbeard, is the captain of the Blackbeard Pirates and one of the Yonko who rule over the second half of the Grand Line, the New World. He was once a member of the Whitebeard Pirates' second division until he murdered Fourth Division commander, Thatch for the Yami Yami no Mi, and defected the crew.

Appearence
Blackbeard is a middle-aged looking man with a massive build (his body is round with relatively thin limbs), a big mouth with several broken or missing teeth (though sometimes he does have a full set; whether this is an inconsistency error made by Oda or part of the story is unknown), a pronounced crooked nose and a very large and hairy chest and torso. Long, thick, curly black hair falls down the back of his neck, underneath a black bandana, and a small scruffy black beard (hence his epithet) grows around his jawline. As the series progresses, his beard becomes longer and scruffier. He is extremely tall, being exactly twice Luffy's (pre-timeskip) height. At the Shichibukai meeting at the Marine Headquarters, he added a pair of necklaces of red as well as golden-yellow and blue beads to his dark orange sash and a traditional black tricorne hat over his grey bandana, as well as switching to a red shirt. He also has three flintlocks and a flask tied to his sash around his waist.

Abilities
Blackbeard has become the first and, so far, only user to wield the powers of two Devil Fruits at the same time. Through unknown means, he acquired the extremely destructive powers of the Gura Gura no Mi from the dead body of Whitebeard and is now able to create earthquakes like his old captain. Marco speculated that this was possible due to an unstated peculiarity unique to Blackbeard himself, having to do with an "atypical body structure" of some sort. He also pointed out that the other Whitebeard Pirates should be aware of this fact. Teach also appears to be knowledgeable enough to know how to use the Gura Gura no Mi powers straight away after extracting it.

Yami Yami no Mi
Blackbeard has eaten the Logia-class Devil Fruit Yami Yami no Mi. With it, he can manipulate gravity, shown as an ebbing shroud of darkness. Teach demonstrates that the "darkness" is a void which devours anything, able to pull in (much in the manner of an actual black hole), and crush his surrounding environment into a pile of rubble. Due to the Yami Yami no Mi's gravitational ability, Blackbeard, unlike every other Logia user, cannot disperse and let attacks simply pass through him, drawing the attacks faster towards himself instead, meaning he takes equivalent or more damage than a normal human would.

Gura Gura no Mi
With the newly acquired powers of the Gura Gura no Mi, which is said to be the strongest Paramecia-class Devil Fruit, Blackbeard can create shock waves by shattering the air itself, creating devastating earthquakes that can destroy the Marineford main building itself. He can also focus his quake powers into a "quake bubble" on his fist, greatly increasing the damage in a single punch. He acquired this fruit after wrapping a black tarp over himself and Whitebeard. The process of how he got it is still unknown, though it can be assumed that he used the power of the Yami Yami no Mi in some way to acquire this power.