The Collaborative International Dictionary of English v.0.48:

Procrastinator \Pro*cras"ti*na`tor\, n.
   One who procrastinates, or defers the performance of
   anything.
   [1913 Webster]

WordNet (r) 3.0 (2006):

procrastinator
    n 1: someone who postpones work (especially out of laziness or
         habitual carelessness) [syn: procrastinator, postponer,
         cunctator]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "procrastinator":
   bungler, dawdle, dawdler, disregarder, dodger, drone, foot-dragger,
   goldbrick, goof-off, idler, ignorer, laggard, lie-abed, lingerer,
   loiterer, malingerer, neglecter, negligent, plodder, shirker,
   slacker, sleepyhead, sloven, slow goer, slow-foot, slowbelly,
   slowpoke, slug, sluggard, slut, snail, stick-in-the-mud, tortoise,
   trifler, waiter on Providence