peace officer (n.)

• bailiff
• beadle
• beagle
• captain
• commissioner
• constable
• cop
• deputy
• detective
• fed
• federal
• gendarme
• inspector
• lieutenant
• marshal
• narc
• officer
• patrolman
• police
• policeman
• policewoman
• reeve
• roundsman
• sergeant
• sheriff
• superintendent
• tipstaff
• trooper