Fiona Shaw CBE is an Irish actress and theatre and opera director.

She is known for her roles as Petunia Dursley in the Harry Potter film series and also as Carolyn Martens in the BBC series Killing Eve, for which she won the 2019 BAFTA TV Award for Best Supporting Actress. For her performances in the second seasons of Killing Eve and Fleabag, she received Primetime Emmy Award nominations for Outstanding Supporting Actress in a Drama Series and Outstanding Guest Actress in a Comedy Series respectively. For the third season of Killing Eve, she was again nominated for Outstanding Supporting Actress in a Drama Series. Shaw has worked with both the Royal Shakespeare Company and the National Theatre. She won the Olivier Award for Best Actress in 1990 and 1994 and the 1997 Drama Desk Award for Outstanding Solo Performance for The Waste Land. Her other stage work includes playing the title role in Medea in the West End and on Broadway (2001–2002). She was awarded the CBE for services to drama in 2001. In 2020, she was named by The Irish Times in their Top 30 list of Ireland’s greatest film actors.