Who are some of the biggest celebrities that have gone to drug abuse rehabilitation?

Some big celebrities that have gone to drug abuse rehabilitation are Charlie Sheen,Robert Downey, Jr,Betty Ford,Marshall Mathers (aka Eminem), Whitney Houston,Elton John. And the list goes on and on. Check out here if you want to see more http://therapistunlimited.com/rehabs/Articles/Drug+Rehabs/Celebrity+Rehab