
Acting
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).

Vicious
as Mother

National Memorial Day Concert
as Self

Unpregnant
as Debra Clarke

Treehouse
as Lilith

Still Laugh-In: The Stars Celebrate
as Self

Drone
as Ellen

The Crash
as Sarah Schwab

Alien Code
as Rebecca

A Country Called Home
as Amanda

An American Girl Story: Maryellen 1955 - Extraordinary Christmas
as Kay Larkin

The Pitt
as Dr. Linda Conley · 2 ep.

Heels
as Willie Day · 16 ep.

The L Word: Generation Q
as Anne Finley · 1 ep.

25 Words or Less
as Mary McCormack · 1 ep.

For the People
as Chloe Daniels · 1 ep.

The Kids Are Alright
as Peggy Cleary · 23 ep.

Will & Grace
as Janet · 2 ep.

Loaded
as Casey · 8 ep.

Chelsea
as Self · 2 ep.

Angie Tribeca
as Abigail Liukin · 3 ep.
1998