Hitman

Hitmen are hostile hired killers

Burke's hitmen
These killers only appear if the Lone Wanderer has disarmed the bomb in Megaton. They are hired Talon Company mercs, in which they greet with a threat, cannot be bargained with, and then proceed to open fire on their victims. They carry a contract for extermination signed by Mister Burke, even if he is dead.

Abolitionist hitmen
These killers appear once the Strictly Business quest has been completed, or if a certain number of people (number required unknown) are enslaved. These hitmen look like wastelanders, greet their victims as "Slaver scum," and then proceed to attack. These hitmen carry the Contract killing note demanding "Wasteland justice."

Appearances
Hitmen only appear in Fallout 3.