Is there a slang word for a hired gun, that is specifically not supposed to kill the subject, just intimidate them? For example, if a political candidate accepted help from a powerful person in order to get elected to office and promised to pay back the favor in the future and when it comes time for the favor, he doesn't want to do it, then the powerful figure might hire someone to intimidate the politician into keeping up his end of the bargain.
The word is goon:
A thug hired to intimidate or harm opponents. (American Heritage, 1st sense, tagged slang)
a thug hired to commit acts of violence or intimidation, esp in an industrial dispute. (Collins, 2nd sense, same link, tagged informal US)
Actually, intimidator works pretty well.
intimidator: one who intimidates
intimidate: to force into or deter from some action by inducing fear
While not all intimidators are hired by powerful people, it's not hard to imagine intimidator being used in that context.
In the criminal parlance of London's 'East End' in the 1950's and 60's, the heyday of the Kray and the Richardson crime families, "the boys would be sent round" to put the "frightners on" some fellow criminal who'd fallen out-of-line or on some poor, innocent individual who hadn't "coughed up" the protection money that was due.
a "standover man" is a man who has been hired by his boss to literally "stand over" you with his height and bulk and threaten reprisals if you do not do what his employer wants.