hatchet man
noun
1- informal a person employed to carry out controversial or disagreeable tasks, such as the dismissal of a number of people from employment〈非正式〉心腹执事（指受雇做麻烦事, 如解雇员工等的人）, 亲信。
1.1
- a person who writes fierce attacks on others or their work对某人（或其工作）作激烈书面攻击者。
词源
late 19th cent. (originally US)： figuratively, from an early use denoting a hired Chinese assassin.