Thanks to everyone for sending the heads up about Carlton Cuse's recent tweets about a clue for an actor that would appear in Season 6 in a guest role.
It seems several fans guessed right and Cuse confirmed that William Atherton would appear.
Here is a link to the Tweet from Cuse and an IMDB link for Atherton:
http://twitter.com/CarltonCuse/status/5222559154
http://www.imdb.com/name/nm0040472/
Posted By: The ODI