The Collaborative International Dictionary of English v.0.48:

Dynamiter \Dy"na*mi`ter\, n.
   One who uses dynamite; esp., one who uses it for the
   destruction of life and property.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dynamiter
    n 1: a person who uses dynamite in a revolutionary cause [syn:
         dynamiter, dynamitist]

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "dynamiter":
   annihilator, arsonist, biblioclast, bomber, burner, demolisher,
   destroyer, dynamitard, exterminator, hun, iconoclast, idol breaker,
   idoloclast, nihilist, ruiner, syndicalist, terrorist, vandal,
   wrecker