. An executioner, also known as a hangman or headsman, is an official who effects a sentence of capital punishment on a condemned person. Scope and job. The executioner was usually presented with a warrant authorising or ordering him to execute the sentence. The warrant protects the executioner from the charge of murder. Common terms for executioners derived from forms of capital punishment—though they often also performed other physical punishments—include hangman (hanging) and headsman (beheading). In the military, the role of executioner was performed by a soldier, such as the provost.
https://en.wikipedia.org/wiki/Executioner