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]