Former Hills' star Lauren Conrad won $50,000 on Who Wants To Be A Millionaire? Wednesday night for her charity, m.powerment by mark, which fights relationship abuse. Conrad, who is now an author and clothing designer, answered the question: "For years, Prince William has had a highly publicized on-again/off-again relationship with a girl named what?" "I think I know this one!" Conrad yelled. She used her lifeline and, with the audiences help, got the correct answer: Kate! (Photo: WENN)