The Collaborative International Dictionary of English v.0.48:

Brawler \Brawl"er\, n.
   One that brawls; wrangler.
   [1913 Webster]

   Common brawler (Law), one who disturbs a neighborhood by
      brawling (and is therefore indictable at common law as a
      nuisance). --Wharton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

brawler
    n 1: a fighter (especially one who participates in brawls)

Moby Thesaurus II by Grady Ward, 1.0:

93 Moby Thesaurus words for "brawler":
   agitator, battler, belligerent, belted knight, bickerer,
   bitter-ender, blade, bravo, bully, bullyboy, combatant, competitor,
   contender, contestant, defendant, diehard, disputant, dissentient,
   dissident, duelist, enforcer, extremist, fencer, feuder, fighter,
   fighting cock, foilsman, frondeur, gamecock, gladiator, goon,
   gorilla, hatchet man, hood, hoodlum, hooligan, insubordinate,
   insurgent, insurrectionary, insurrectionist, insurrecto,
   intransigent, irreconcilable, jouster, knight, last-ditcher,
   litigant, malcontent, maverick, militant, mutineer, naysayer,
   negativist, nonconformist, noncooperator, objector, obstructionist,
   obstructive, opposer, oppositionist, plaintiff, plug-ugly,
   protester, quarreler, rebel, resister, revolter, revolutionary,
   revolutionist, rioter, rival, rough, rowdy, ruffian, sabreur,
   scrapper, scuffler, squabbler, strong arm, strong-arm man,
   strong-armer, struggler, subversive, swashbuckler, sword,
   swordplayer, swordsman, thug, tilter, tough, traitor, tussler,
   wrangler