
Plainfield, New Jersey, USA
Mary Catherine McCormack is an American actress. She has had leading roles as Justine Appleton on the series Murder One (1995–1997), as Deputy National Security Adviser Kate Harper on The West Wing (2004–2006), as Deputy U.S. Marshal Mary Shannon on In Plain Sight (2008–2012), and as Peggy on the comedy series The Kids Are Alright (2018–2019).

as Mary Shannon

as Rickie the Bartender
1990

as Self - Guest
2009

as Mary Shannon
2001

as Debbie
1994

as Kate Harper
1999

as Dr. Linda Conley
2025

as Self
2005

as Lisa Elliot
2012

as Self
2003

as Self - Nominee
1956

as Self
2003

1992
as Debra Clarke
2020

as Mother
2025

as Self
2023

as Debra Clarke
2020

as Self
2019

as Lilith
2019

as Ellen
2017

as Rebecca
2017

as Sarah Schwab
2017

as Kay Larkin
2016

as Amanda
2016

as Ms. Richards (voice)
2014

as Leann
2013

as Ellen
2012
as Hilary Pfeiffer-Dunne
2012

as Lilly Enslin
2007

as Pilgrim Woman
2006

as Lexi
2006

as Bonnie McCormick
2005

as Grace Finney
2003

as Linda
2002

as Margaret
2002

as Rachel Powell
2001

as Frances
2001

as Phoebe
2001
as Mary Shannon
1 ep.

as Rickie the Bartender
1 episodes

as Self - Guest
1 episodes

as Mary Shannon
1 episodes

as Debbie
6 episodes

as Kate Harper
48 episodes

as Dr. Linda Conley
2 episodes

as Self
2 episodes

as Lisa Elliot
1 episodes

as Self
1 episodes

as Self - Nominee
1 episodes

as Self
1 episodes

1 episodes

as Molly Levy
2 episodes

as Self
26 episodes

as Mary Shannon
61 episodes

as Justine Appleton
41 episodes

as Self
1 episodes

as Self
2 episodes

as Self - Panelist
1 episodes

as Abigail Liukin
3 episodes

as Self - Panelist
1 episodes

as Janet
2 episodes

as Denna Altshuler
7 episodes

as Chloe Daniels
1 episodes