One of the most controversial and successful female vocalists of the 2000s, Britney Spears (along with the Backstreet Boys and 'N Sync) spearheaded the rise of post-millennial teen pop. She then spearheaded what looked like her own demise, with her questionable parenting, substance abuse and generally bizarre behavior becoming constant tabloid fodder. But as the 2000s closed, Spears seemed to have righted her ship and still held much of her popular appeal.