The Collaborative International Dictionary of English v.0.48:

individualist \individualist\ n.
   a person who pursues independent thought or action.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

individualist
    adj 1: marked by or expressing individuality; "an
           individualistic way of dressing" [syn: individualist,
           individualistic]
    n 1: a person who pursues independent thought or action

Moby Thesaurus II by Grady Ward, 1.0:

55 Moby Thesaurus words for "individualist":
   Narcissus, anomaly, braggart, capitalist, careerist, crosspatch,
   egocentric, egoist, egotist, fortune hunter, freak, free lance,
   free spirit, free trader, freethinker, hog, independent,
   individualistic, inner-directed person, isolationist, know-it-all,
   latitudinarian, liberal, libertarian, libertine, lone wolf, loner,
   maverick, misfit, monopolist, mugwump, narcissist, narcist,
   naysayer, neutral, no modest violet, nonconformist, nonpartisan,
   oddball, rich man, road hog, rugged individualist, self-advancer,
   self-pleaser, self-seeker, self-server, smart aleck, sport,
   swellhead, temporizer, third force, third world, timepleaser,
   timeserver, tufthunter