House - "House Divided"
Heroes - "An Invisible Thread"
Lie To Me - "Undercover"
D.B. Woodside guest starred as 'Henry Strong.' Buffy the Vampire Slayer fans will remember him as 'Principal Robin Wood' from season 7. His character was significant because Spike killed his mom, who was a slayer, and then wore her jacket.
Dollhouse - "Briar Rose"
Alan Tudyk guest starred as 'Alpha' posing as 'Stephen Kepler' designer of the Dollhouse. Alan is a Whedon alumni since starred in the all too short-lived series Firefly as 'Wash,' which evolved into the movie Serenity. You may also remember him from Dodgeball: A True Underdog Story as 'Steve the Pirate.'