Source : Webster's Revised Unabridged Dictionary (1913)

Troubler \Trou"bler\, n.
   One who troubles or disturbs; one who afflicts or molests; a
   disturber; as, a troubler of the peace.

         The rich troublers of the world's repose. --Waller.

Source : WordNet®

troubler
     n : someone who deliberately stirs up trouble [syn: {troublemaker},
          {trouble maker}, {mischief-maker}, {bad hat}]