negativist

negativist
    n 1: someone who refuses to do what is asked or does the
         opposite of what is asked
    2: someone who is resigned to defeat without offering positive
       suggestions [syn: {defeatist}, {negativist}]
    

45 Moby Thesaurus words for "negativist":
      Cassandra, Eeyore, bitter-ender, brawler, calamity howler, cynic,
      defeatist, defendant, diehard, disputant, dissentient, dissident,
      filibuster, filibusterer, frustrater, hinderer, impeder,
      intransigent, irreconcilable, killjoy, last-ditcher, litigant,
      malist, marplot, naysayer, nihilist, noncooperator, objector,
      obstructer, obstructionist, obstructive, opposer, oppositionist,
      pessimist, plaintiff, prophet of doom, protester, quarreler,
      resister, retreatist, scrapper, seek-sorrow, thwarter, worrywart,
      wrangler