The Collaborative International Dictionary of English v.0.48:

Truckler \Truc"kler\, n.
   One who truckles, or yields servilely to the will of another.
   [1913 Webster]

WordNet (r) 3.0 (2006):

truckler
    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]