Will Smith death hoax.

http://www.snopes.com/computer/facebook/willsmithdead.asp

those reports are being spread by a malicious Facebook app. When users are tricked into clicking through on these fake "R.I.P. Will Smith" posts to see the promised news videos, they end up installing a rogue app that posts the same very thing to other Facebook pages in their name. 

Facebook's Desktop Help section provides users with instructions on how to remove unwanted apps.

http://www.snopes.com/inboxer/hoaxes/cliffdeath.asp