
Actor
Mary McCormack
Born 1969 · 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).
Acting

The Pitt
Dr. Linda Conley · 2025

K-PAX
Rachel Powell · 2001

1408
Lilly Enslin · 2007

ER
Debbie · 1994

The Newsroom
Molly Levy · 2012

The West Wing
Kate Harper · 1999

Deep Impact
Andrea Baker · 1998

Law & Order
Rickie the Bartender · 1990

Miracle on 34th Street
Myrna Foy · 1994

Scandal
Lisa Elliot · 2012

Law & Order: Criminal Intent
Mary Shannon · 2001

True Crime
Michelle Ziegler · 1999

Scooby-Doo! WrestleMania Mystery
Ms. Richards (voice) · 2014

Unpregnant
Debra Clarke · 2020

Private Parts
Alison Stern · 1997

Heels
Willie Day · 2021

The L Word: Generation Q
Anne Finley · 2019

54
New Year's Eve Wife (uncredited) · 1998

House of Lies
Denna Altshuler · 2012

Mystery, Alaska
Donna Biebe · 1999

Will & Grace
Janet · 2017

Vicious
Mother · 2025

In Plain Sight
Mary Shannon · 2008

The Late Late Show with Craig Ferguson
Self · 2005