enforcer

noun

1. a person or thing that enforces.
2. the member of a group, especially of a gang, charged with keeping dissident members obedient.
3. a person, especially a public official, who enforces laws, regulations, rules, or the like.
4. Also called policeman. Ice Hockey. a physically intimidating or willingly belligerent player who is counted on to retaliate when rough tactics are used by the opposing team.