Macdonald's career began while she was working as a barmaid in Glasgow. She saw a leaflet advertising an open casting session for
Trainspotting and decided to audition, winning the part of Diane, the underage seductress to
Ewan McGregor's Renton. Other roles include Mary O'Neary in
Two Family House, and an actress playing
Peter Pan in
Finding Neverland. She had major roles in
Robert Altman's British
period piece Gosford Park, where she played an
aristocrat's maid, and in
Intermission (2003), as Deirdre. On radio she portrayed Mary in the 1999 BBC radio drama
Lifehouse, based on
Pete Townshend's abandoned rock opera, some of the songs for which were released on
The Who's album ''
Who's Next. On television, her highest profile roles have been in two BBC dramas, the Paul Abbott serial State of Play (2003), and the one-off Richard Curtis piece The Girl in the Café (2005). Both of these were directed by David Yates, and both also starred Bill Nighy. For her performance in The Girl in the Café'', she was nominated for the
Golden Globe Award for Best Actress – Miniseries or Television Film in 2006, and won the
Primetime Emmy Award for Outstanding Supporting Actress in a Miniseries or a Movie. Macdonald had a supporting role in the
Coen brothers'
Academy Award-winning film
No Country for Old Men (2007), for which she was nominated for a
BAFTA Award for Best Actress in a Supporting Role. It was reported that she had to fight her agent to be considered for the role, but Macdonald later denied the story. Other films where she had supporting roles include
Choke (2008), adapted by
Clark Gregg from the 2001
Chuck Palahniuk novel, as Paige Marshall;
In the Electric Mist (2009) (based on
James Lee Burke's
In the Electric Mist with Confederate Dead (1993), as Kelly Drummond, alongside
Tommy Lee Jones and
John Goodman; and
Skellig (2009), as Louise. She played the lead in
The Merry Gentleman (2008). In 2011 she played the "
Grey Lady" (revealed to be
Helena Ravenclaw) in
Harry Potter and the Deathly Hallows – Part 2, the final instalment of the
Harry Potter film franchise. She replaced
Nina Young, who originally played the role. In 2012, she provided the voice of
Merida, the heroine of the
Disney/
Pixar film
Brave, and played Dolly in
Anna Karenina. She starred in the romantic comedy film
The Decoy Bride, which was released in 2012. From 2010 until its ending in 2014, she starred in the
HBO crime drama
Boardwalk Empire as
Margaret Thompson, the wife of
Prohibition-era Atlantic City crime boss
Nucky Thompson (
Steve Buscemi). She appeared in all five seasons of the series. In 2011, she and the rest of the show's cast were awarded the
Screen Actors Guild Award for Outstanding Performance by an Ensemble in a Drama Series. In 2016 she starred in
Ricky Gervais'
Special Correspondents as Claire Maddox, and
Swallows and Amazons as Mrs. Walker. In 2016, she played the lead role in "
Hated in the Nation", an episode of the
anthology series Black Mirror for which she received critical acclaim. On 3 November 2016 Macdonald was featured in the trailer for
Danny Boyle's
T2 Trainspotting confirming she would reprise her role as Diane from the original film, which she did. In 2017, she co-starred opposite
Benedict Cumberbatch in the
BBC film
The Child in Time. Macdonald played the guest lead in the sixth series of the BBC's police drama
Line of Duty. In 2025 Macdonald appeared as a therapist in the
Netflix thriller
Dept. Q; her next role will be as a sheriff in the HBO series
Lanterns. ==Personal life==