The Collaborative International Dictionary of English v.0.48:

Groveler \Grov"el*er\, n.
   One who grovels; an abject wretch. [Written also
   --groveller.]
   [1913 Webster] groveling

WordNet (r) 3.0 (2006):

groveler
    n 1: someone who humbles himself as a sign of respect; who
         behaves as if he had no self-respect [syn: apple
         polisher, bootlicker, fawner, groveller, groveler,
         truckler]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "groveler":
   apple-polisher, ass-licker, backscratcher, backslapper, bootlick,
   bootlicker, brown-nose, brownie, clawback, courtier, creature,
   cringer, dupe, fawner, flatterer, flunky, footlicker, handshaker,
   helot, instrument, jackal, kowtower, lackey, led captain, lickspit,
   lickspittle, mealymouth, minion, peon, puppet, serf, slave,
   spaniel, stooge, suck, sycophant, timeserver, toad, toady, tool,
   truckler, tufthunter, yes-man