The Collaborative International Dictionary of English v.0.48:

Occupier \Oc"cu*pi`er\, n.
   1. One who occupies, or has possession.
      [1913 Webster]

   2. One who follows an employment; hence, a tradesman. [Obs.]
      "Merchants and occupiers." --Holland.
      [1913 Webster]

            The occupiers of thy merchandise.     --Ezek. xxvii.
                                                  27.
      [1913 Webster]

WordNet (r) 3.0 (2006):

occupier
    n 1: someone who lives at a particular place for a prolonged
         period or who was born there [syn: resident, occupant,
         occupier] [ant: nonresident]
    2: a member of a military force who is residing in a conquered
       foreign country