The Collaborative International Dictionary of English v.0.48:

Controversialist \Con`tro*ver"sial*ist\, n.
   One who carries on a controversy; a disputant.
   [1913 Webster]

         He [Johnson] was both intellectually and morally of the
         stuff of which controversialists are made. --Macaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

controversialist
    n 1: a person who disputes; who is good at or enjoys controversy
         [syn: disputant, controversialist, eristic]