Hailing from Edmonton, Canada, Hennessy began her acting career in Toronto, appearing in the feature film �Dead Ringers.� She studied improvisational comedy with the famed Second City and also worked with a Toronto-based improv comedy troupe before landing a role in the Broadway-bound production of �The Buddy Holly Story.�
Once in New York, Hennessy starred in Ron Howard�s feature film �The Paper.� Her additional film credits include �I Shot Andy Warhol,� �Chutney Popcorn,� �Most Wanted,� �A Smile Like Yours,� �Dead Broke,� �Row Your Boat,� �The Florentine,� �Two Ninas,� �Molly,� �Autumn in New York� and the box-office hit �Exit Wounds.� Hennessy also performed in �The Acting Class,� a documentary style depiction of the dark side of the teacher/student relationship, which she also wrote and co-directed. Most recently, she was seen in the Robert Redford/Sundance Lab project, �Love in the Time of Money.�
Prior to the success of �Crossing Jordan,� television audiences knew Hennessy from the years (1993-96) she spent playing the role of assistant district attorney Claire Kincaid on the Emmy-winning NBC drama series �Law & Order.� She returned to NBC by starring as First Lady Jacqueline Kennedy in the miniseries �Jackie, Ethel, Joan: Women of Camelot.�
For her work on �Crossing Jordan� in its premiere season, Hennessy received a People�s Choice Award nomination for Best Actress in a Drama Series. She has also received a Golden Satellite Award (Best Performance by an Actress in a Miniseries or a Motion Picture Made for Television) from the International Press Academy for her work in the cable movie �Nuremberg.�
Hennessy and her husband, Paolo Mastropietro, recently welcomed their first child. The family divides their time between their homes in Los Angeles and Manhattan.