Executioner

The Executioner is a multiplayer character in Assassin's Creed: Brotherhood. The Executioner uses an axe as his primary weapon. The Templar Cross is clearly visible upon his axe. It is said by Ubisoft that he will make an appearance in some form in the single-player mode of Assassin's Creed: Brotherhood as well, along with the rest of the multiplayer characters.

Culling Blade
The Executioner grabs his target from behind and pulls the victim down to his/her knees, while holding the victim with a firm grip, he raises his axe above his head and digs it into the victim's back with force. Twice.

Body Smash
The Executioner sneaks behind his target and grabs him/her from the side of his body, he then lifts the victim into the air and smashes the victim into the ground, head-first. The victim's weight will be pushed to the back of the neck and the weight will be too heavy for the neckbone, thus snapping the bone

This can be performed from the front as well.