The Collaborative International Dictionary of English v.0.48:

Self-willed \Self`-willed"\, a.
   Governed by one's own will; not yielding to the wishes of
   others; obstinate.
   [1913 Webster]

WordNet (r) 3.0 (2006):

self-willed
    adj 1: habitually disposed to disobedience and opposition [syn:
           froward, headstrong, self-willed, willful,
           wilful]

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "self-willed":
   balking, balky, bigoted, bulldogged, bulletheaded, bullheaded,
   case-hardened, contrary, contumacious, determined, difficult,
   disobedient, dogged, dogmatic, fanatic, forceful, froward,
   hardheaded, headstrong, heady, incorrigible, indisciplined,
   insubordinate, intolerant, intractable, irresponsible, lawless,
   licentious, mulish, mutinous, naughty, nonconforming, obstinate,
   opinionated, overzealous, persevering, pertinacious, perverse,
   pigheaded, rampant, recalcitrant, recusant, refractory, reinless,
   restive, set, stiff-necked, strong-willed, strongheaded, stubborn,
   sulky, sullen, tenacious, transgressive, unaccountable, unbridled,
   unchecked, uncomplying, uncontrollable, uncontrolled,
   uncooperative, uncurbed, undisciplined, unduteous, undutiful,
   ungovernable, ungoverned, unmanageable, unregenerate, unreined,
   unrestrained, unruly, vexatious, violative, wayward, wildcat,
   willful