Fenrir Greyback
Background
Fenrir Greyback is a werewolf and a member of the Death Eaters. He infected Professor Lupin with lycanthropy during an attack.
During the events of Harry Potter and the Half-Blood Prince (2009) played by Dave Legeno
A group of Death Eaters attack targeted areas of Diagon Alley including Ollivander's shop where Fenrir drags out Mr Ollivander and takes him captive. The Death Eaters then attack parts of London and cause the collapse of the Millennium Bridge. Later, the Weasley house is attacked by Death Eaters including Bellatrix Lestrange and Fenrir. Draco Malfoy uses the Vanishing Cabinet to let Bellatrix, Fenrir and three other Death Eaters into Hogwarts. Draco walks up to Albus Dumbledore and shows him his Death Eater tattoo and tells Dumbledore that he was chosen by Voldemort to kill him. Draco casts Expelliarmus on Dumbledore, disarming him. Bellatrix, Fenrir, Amycus, Alecto, and Rowle walk over to Draco and Professor Snape goes to where the others are and casts Avada Kedavra on Dumbledore, killing him. Snape leaves with the Death Eaters who, as they are leaving cause destruction within Hogwarts and burn down Hagrid's hut. Harry Potter attacks Snape and Bellatrix stuns Harry with a spell. Snape reveals himself to be the Half-Blood Prince and walks away.