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]