night watchman

noun3

1. •
   A person who guards (usually at a building) at night.

   • We can hear the night watchman click his flashlight / Ask himself if it's him or them that's insane — 1966
2. •
   (historical) Prior to police forces, a person appointed by a town or city to walk the streets at night and guard the burghers from felons and robbers.
3. •
   A lower order batter to play the last overs in low light to save better batters for the next day's play.