Marvel was born in Orange County, California, and was raised in Mohnton, Pennsylvania. She attended Juilliard School and since the early 1990s has appeared in off-Broadway plays.
Marvel appeared in many stage productions throughout her career. Her first professional role was as Isabella in Measure for Measure at Canada's Stratford Festival in 1992. She has won Obie Awards for her work in Thérèse Raquin and Misalliance (1998), A Streetcar Named Desire (2000) and Hedda Gabler (2005). She returned to the role she originated Off-Broadway of Brooke Wyeth in Other Desert Cities, which was played by Rachel Griffiths in its Broadway premiere. In 2009, for her performance in Fifty Words, she was nominated for a Drama Desk Award for Outstanding Actress in a Play.
Marvel first gained widespread attention on television, with her four seasons playing the regular role of Nancy Parras in the CBS series The District (2000–04). She played a variety of guest and recurring roles on Lights Out, Law & Order: Special Victims Unit, Nurse Jackie, Person of Interest, 30 Rock, The Good Wife, and The Newsroom.
Marvel married actor Bill Camp on September 4, 2004. The couple has one child.
In film, Marvel has appeared in Burn After Reading (2008), directed by the Coen brothers, and in True Grit (2010), as the adult Mattie Ross. She appeared in The Bourne Legacy (2012), Lincoln (2012), and Hyde Park on Hudson (2012).
In 2013, she was cast as lead in the CW family drama pilot Blink, opposite John Benjamin Hickey. She most recently was noted for portraying Heather Dunbar in Netflix's political drama House of Cards. In 2016, she was cast as President-elect Elizabeth Keane for the sixth and seventh seasons of Showtime drama series Homeland.
