The Hangmen consisted of Breathtaker (no relation to the similarly named Firestorm villain). Provoke, Shock Trauma, Stranglehold, and Killshot. They were assassins hired by nationals from Quarac, a Middle Eastern country, to assassinate the terrorist known as Cheshire. Later on, the Hangmen targeted Cheshire's daughter Lian Harper. However, Lian was saved by her father, Roy Harper, the hero known as Arsenal. They were initially beaten by the Titans, who they would again encounter.
Breathtaker and Stranglehold were later seen as part of Circe's all villainess army. Following that, the Hangmen joined the Secret Society of Super Villains. It turned out the mercenary group used the Society's full scale assault on Metropolis as a cover to loot the city. Dr. Psycho later found out about their duplicity and sent members of the Society to kill them. All the members were apparently brutally killed except Stranglehold. Stranglehold later appeared in Salvation Run.
All of the Hangmen appeared alive in Final Crisis Revelations. It turned out that Dr.Psycho had helped them fake their own deaths, so that they could continue their illicit activities without drawing attention from the superhero community. Libra offered the Hangmen membership in his Secret Society of Super Villains, but during this even, the Spectre showed up with the intention to kill Libra. Libra managed to escape, leaving the members of the Hangmen to their deaths at the hands of the Spectre.
Recently, a new team as emerged with all new members, using the same identities and abilities as the originals.