6) Jeff Conaway
Jeff Conaway is famous for two roles early in his career – Kenickie in the movie Grease and Bobby Taylor on the TV show Taxi. Unfortunately, after his early success and fame he began to use drugs and developed a serious addiction. He was in an out of rehab for many years, never able to permanently exorcise his demons. A couple of years before his death he appeared on Celebrity Rehab with Dr. Drew Pinsky, where he spoke candidly about his difficulties and urged others not to go down the same path. In May, 2011 Conaway died of complications related to drug use.