WordNet (r) 3.0 (2006):

scrapper
    n 1: someone who fights (or is fighting) [syn: combatant,
         battler, belligerent, fighter, scrapper]

Moby Thesaurus II by Grady Ward, 1.0:

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