Yvonne Strahovski worked on NBC , Showtime , and Fox shows .
She is best known for her roles as CIA Agent Sarah Walker in the NBC series Chuck -LRB- 2007 -- 2012 -RRB- , Hannah McKay in the Showtime series Dexter -LRB- 2012 -- 2013 -RRB- and CIA Agent Kate Morgan in the Fox limited event television series 24 : Live Another Day -LRB- 2014 -RRB- .