 Fedak always had Baldwin in mind for the role of John Casey and the producers found that the actor was a "perfect fit" for the character during the first casting session.Relative newcomer Yvonne Strahovski was chosen for the female lead role of what was then CIA officer Sarah Kent in the same month.Casting continued throughout March with Sarah Lancaster, Joshua Gomez, and Natalie Martinez landing the parts of Dr. Ellie Bartowski (Chuck's older sister), Morgan Pace (Chuck's best friend), and Kayla Hart (Chuck's neighbor and love interest), respectively.