The Collaborative International Dictionary of English v.0.48:

Scourger \Scour"ger\, n.
   One who scourges or punishes; one who afflicts severely.
   [1913 Webster]

         The West must own the scourger of the world. --Byron.
   [1913 Webster]

WordNet (r) 3.0 (2006):

scourger
    n 1: a torturer who flogs or scourges (especially an official
         whose duty is to whip offenders) [syn: flogger,
         scourger]