Rise to Success: Career Highlights of Mary McCormack

By Popular Timelines Editorial Team · Updated: April 3, 2026

How Mary McCormack built a successful career. Explore key moments that defined the journey.

Mary McCormack is an American actress known for her versatility across television, film, and stage. She gained significant recognition for her role as Justine Appleton in the crime drama "Murder One" (1995-1997) and later starred as Deputy National Security Advisor Kate Harper in the political drama "The West Wing" (2004-2006). She is also recognized for her comedic roles, including her lead role as Mary Shannon in the USA Network series "In Plain Sight" (2008-2012) about a U.S. Marshal in the Witness Protection Program. Her film credits include "Private Parts", "Deep Impact", "True Crime", and "K-PAX". McCormack has also performed in numerous Broadway and off-Broadway productions.

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Full Timeline Career & Achievements

1995: Starred in Murder One

In 1995, Mary McCormack portrayed Justine Appleton on Murder One.

1997: Starred in Private Parts

In 1997, Mary McCormack starred in Howard Stern's movie Private Parts and also starred in the HBO series K Street.

2004: Joined The West Wing

In 2004, Mary McCormack joined the cast of The West Wing as Deputy National Security Advisor and ex-CIA officer Kate Harper.

July 28, 2010: Renewal of In Plain Sight

On July 28, 2010, the show "In Plain Sight", starring Mary McCormack, was renewed for its fourth and fifth seasons, to run in 2011 and 2012.

2011: End of In Plain Sight

In 2011, the USA Network series In Plain Sight ended after its fifth season. After its end, McCormack was cast as the lead in Kari Lizer's untitled comedy pilot on ABC.

2012: In Plain Sight ended

In 2012, In Plain Sight concluded its run.

2012: Reunion for U.S. Voters

In 2012, Mary McCormack reunited with the cast of The West Wing to film a video to promote nonpartisan voting and her sister's judicial candidacy for the Michigan State Supreme Court.

October 2013: Filming for The Crash began

In October 2013, Mary McCormack began filming scenes for The Crash, also titled A Conspiracy on Jekyll Island.

2016: An American Girl Story Role

In 2016, Mary McCormack played a supporting role in the Amazon.com exclusive special An American Girl Story – Maryellen 1955: Extraordinary Christmas.