Bombers are white masked men who can arrive on the most unexpected places to kill people.
Bombers have a kind like metal like pistol in which fiendfyre comes out, which burns everyone to death. Bombers are actually not-dark death eaters, who have no side. They kill people from the good side and from the dark side with their weapons.
Bombers also can be good in fight, but they want to finish the job quick using their fiendfyre weapon.
Bombers wear white masks and have black hair. Nobody knows how they really look like, is it a creature or a simple human? They are compared with Boggarts, whose face is also not seen in the series.
APPEARANCES IN THE SHOW:
The Eater Busts.
Four Bombers arrive in the Unsub basement to kill Ron Weasley, but Weasley escapes and seals them in a room, but they disappear before Ron can take a look. They later appear again to kill Ron and Dumbeldore both. It ends up with fight, burning Dumbeldore's leg severely. Dumbeldore kills them with a four double Avada Kedrava curse which changes them in ashes.
They come at Gringotts to kill all the Death Eaters there. It eventually works. All the death eaters are burned alive and killed in 1998.
Six bombers arrive at Ministry Of Magic to kill Puck, Guus, Harry Potter, Draco Malfoy, Ron Weasley and Hermoine Granger and Dumbeldore. They escape, but Minister of Magic named Fudge is tortured and killed by the Bombers together with a group of assistents. They later appear as Puck is in custody by a group of protectors, but they where killed by a Curse Of Death hit by Dumbeldore.
The Bombers arrive at the camp and kill a group of infiltrators, including The Western Revolver Man.