Mary McCormack
Biography
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).
Known For
Watch What Happens Live with Andy Cohen
2009
Law & Order
1990
The Late Late Show with Craig Ferguson
2005
Jimmy Kimmel Live!
2003
Law & Order: Criminal Intent
2001
The West Wing
1999
The Pitt
2025
ER
1994
The Tonight Show with Jay Leno
1992
Scandal
2012
The Ellen DeGeneres Show
2003
0Tony Awards
1956
Filmography
Watch What Happens Live with Andy Cohen
as Self - Guest · 2009
Law & Order
as Rickie the Bartender · 1990
The Late Late Show with Craig Ferguson
as Self · 2005
Jimmy Kimmel Live!
as Self · 2003
Law & Order: Criminal Intent
as Mary Shannon · 2001
The West Wing
as Kate Harper · 1999
The Pitt
as Dr. Linda Conley · 2025
ER
as Debbie · 1994
The Tonight Show with Jay Leno
· 1992
Scandal
as Lisa Elliot · 2012
The Ellen DeGeneres Show
as Self · 2003
Tony Awards
as Self - Nominee · 1956
25 Words or Less
as Self · 2018
25 Words or Less
· 2018
25 Words or Less
as Mary McCormack · 2018
Late Night with Jimmy Fallon
as Self · 2009
The Late Late Show with Craig Kilborn
as Self - Guest · 1999
In Plain Sight
as Mary Shannon · 2008
Chelsea
as Self · 2016
The Newsroom
as Molly Levy · 2012
Angie Tribeca
as Abigail Liukin · 2016
Will & Grace
as Janet · 2017
To Tell the Truth
as Self - Panelist · 2016
Murder One
as Justine Appleton · 1995
Match Game
as Self - Panelist · 2016
House of Lies
as Denna Altshuler · 2012
Deep Impact
as Andrea Baker · 1998
For the People
as Chloe Daniels · 2018
Divorce
as Kathy DeSantis · 2016
The L Word: Generation Q
as Anne Finley · 2019
1408
as Lilly Enslin · 2007
Heels
as Willie Day · 2021
Miracle on 34th Street
as Myrna Foy · 1994
K-PAX
as Rachel Powell · 2001
K Street
as Maggie Morris · 2003
Traffic
as Carole McKay · 2004
Welcome to the Family
as Caroline Yoder · 2013
True Crime
as Michelle Ziegler · 1999
The Kids Are Alright
as Peggy Cleary · 2018
Vicious
as Mother · 2025
54
as New Year's Eve Wife (uncredited) · 1998
Private Parts
as Alison Stern · 1997
Full Frontal
as Linda · 2002
Mystery, Alaska
as Donna Biebe · 1999
Drone
as Ellen · 2017
Gun Shy
as Gloria Nesstra · 2000
Fathers' Day
as Virginia Farrell (uncredited) · 1997
Scooby-Doo! WrestleMania Mystery
as Ms. Richards (voice) · 2014
Right at Your Door
as Lexi · 2006
Dickie Roberts: Former Child Star
as Grace Finney · 2003
For Your Consideration
as Pilgrim Woman · 2006
Loaded
as Casey · 2017
High Heels and Low Lifes
as Frances · 2001
The Broken Hearts Club: A Romantic Comedy
as Anne · 2000
The Wright Verdicts
as Beth Eckhart · 1995
Unpregnant
as Debra Clarke · 2020
Treehouse
as Lilith · 2019
Still Laugh-In: The Stars Celebrate
as Self · 2019
The Crash
as Sarah Schwab · 2017
Getting to Know You
as Leila Lee · 1999
Should've Been Romeo
as Ellen · 2012
A Country Called Home
as Amanda · 2016
The Alarmist
as Sally · 1998
Backfire!
as Sarah · 1995
Chelsea Does
as Herself · 2016
Murder One: Diary of a Serial Killer
as Justine Appleton · 1997
Alien Code
as Rebecca · 2017
Escape from Polygamy
as Leann · 2013
The Big Tease
as Monique · 1999
An American Girl Story: Maryellen 1955 - Extraordinary Christmas
as Kay Larkin · 2016
Colin Fitz
as Moira · 1997
BigLove
as Phoebe · 2001
National Memorial Day Concert
as Self · 2023
Harvest
as Agent Becka Anslinger · 1999
The Unprofessional
as Hilary Pfeiffer-Dunne · 2012
Madison
as Bonnie McCormick · 2005
World Traveler
as Margaret · 2002
East of A
as Daphne · 2000
Other Voices
as Anna · 2000