chaperon, chaperone - one who accompanies and supervises a young woman or gatherings of young people

admonisher, monitor, reminder - someone who gives a warning so that a mistake can be avoided

bodyguard, escort - someone who escorts and protects a prominent person

paladin, champion, fighter, hero - someone who fights for a cause

custodian, keeper, steward - one having charge of buildings or grounds or animals

fire fighter, fire-eater, firefighter, fireman - a member of a fire department who tries to extinguish fires

foster-parent - a person who acts as parent and guardian for a child in place of the child's natural parents but without legally adopting the child

guard - a person who keeps watch over something or someone

keeper - someone in charge of other people; "am I my brother's keeper?"

law officer, lawman, peace officer - an officer of the law

patron saint - a saint who is considered to be a defender of some group or nation

peacekeeper - someone who keeps peace; "she's the peacekeeper in that family"

preserver - someone who keeps safe from harm or danger

watchdog - a guardian or defender against theft or illegal practices or waste; "she is the global watchdog for human rights abuses"

battler, belligerent, combatant, fighter, scrapper - someone who fights (or is fighting)