The Collaborative International Dictionary of English v.0.48:

Habitu'e \Ha`bi`tu`['e]"\ ([.a]`b[-e]`t[.u]`[asl]"), n. [F., p.
   p. of habituer. See Habituate.]
   One who habitually frequents a place; as, an habitu['e] of a
   theater.
   [1913 Webster]

WordNet (r) 3.0 (2006):

habitue
    n 1: a regular patron; "an habitue of the racetrack"; "a bum who
         is a Central Park fixture" [syn: regular, habitue,
         fixture]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "habitue":
   aficionado, attender, audience, buff, caller, company, customer,
   denizen, devotee, employer, fan, freeloader, frequenter,
   gate-crasher, guest, haunter, hound, lover, moocher, patron,
   regular, regular customer, sojourner, spectator, theatergoer,
   uninvited guest, user, visitant, visitor, votary