trooper (n.)

• bailiff
• beadle
• beagle
• captain
• cavalryman
• charger
• commissioner
• constable
• constabulary
• cossack
• courser
• cuirassier
• deputy
• detective
• dragoon
• fed
• federal
• gendarme
• hussar
• inspector
• lance
• lancer
• lieutenant
• marshal
• narc
• officer
• patrolman
• police
• policeman
• policewoman
• posse
• reeve
• roundsman
• sergeant
• sheriff
• superintendent
• tipstaff