I'm looking for a word (or perhaps a couple of words) to describe a person who willingly takes on the job of doing something unpopular or unkind so that they become the target of resentment for this, rather than their boss/employer.
Example:-
People still trust the politician as he always gets Bob, his ~ to announce the tax rises for him.
"Scapegoat" isn't quite right, because they are usually an unwilling victim.
"Goon" implies the person has low intelligence and implies violence.