Letts will play the role of Sen. Andrew Lockhart. Also joining the cast for the third season are his Virginia Woolf co-star Amy Morton, Joanna Merlin (Solomon's Child), Nazanin Boniadi ("Iron Man") and Lawrence Clayton (Bells Are Ringing).
Rupert Friend and Jackson Pace will return to the series' third season, which will premiere Sept. 29 on Showtime.
"Homeland" also features stage stars Claire Danes (Pygmalion), Damian Lewis (Hamlet), F. Murray Abraham (Mauritius) and Mandy Patinkin (Evita).
Visit Sho.com/Homeland.
