Thatch

Thatch was the commander of the 4th Division of the Whitebeard Pirates.

Appearance
‎Thatch had blonde hair, which went to a point at the back of his head, and some black stubble around his chin. Thatch also had a scar running down his face and had his teeth usually clenched. Thatch also dressed poshly, usually in blue uniform.

Abilities and Power
Having been a division commander, he had authority over a vast number of subordinates.

The New Comrade
Thatch was one of the first to try befriending Ace when he had arrived on the ship.

Getting the Yami Yami no Mi and fight with Blackbeard
Thatch later found the Yami Yami no Mi, the Devil Fruit that Blackbeard was after for a long time. This Devil Fruit was the very reason that Blackbeard joined the Whitebeard Pirates, so he killed Thatch and ran off with it, leading his former commander, Portgas D. Ace, to hunt him down for revenge.

Trivia

 * Seeing a resemblance between Thatch's name and that of the alias of the real life Blackbeard, Edward Thatch, a fan asked Oda, in a SBS question, if Thatch was based on the real life Blackbeard along with Edward Newgate and Marshall D. Teach. Oda replied to the fan that he indeed based Thatch's name on the real life Blackbeard's alias. However, the basis is in name only.
 * It is likely that unlike the other 3 division commanders of the top four, Thatch did not have the power of a Devil Fruit since according to Blackbeard, Thatch was required to eat the Devil Fruit he found, which would have killed him if he had already consumed one.