Source : Webster's Revised Unabridged Dictionary (1913)

Rescuer \Res"cu*er\ (-k?-?r), n.
   One who rescues.

Source : WordNet®

rescuer
     n 1: a person who rescues you from harm or danger [syn: {savior},
           {saviour}, {deliverer}]
     2: someone who saves something from danger or violence [syn: {recoverer},
         {saver}]