Fiona Shaw (born Fiona Mary Wilson, 10 July 1958) is an Irish film and theatre actress. She did extensive work with the Royal Shakespeare Company and the National Theatre, as well as in film and television. In 2020, she was listed at No. 29 on The Irish Times list of Ireland's greatest film actors. She was made an Honorary Commander of the Order of the British Empire (CBE) by Queen Elizabeth II in 2001.

She won both the 1990 and 1994 Laurence Olivier Award for Best Actress for roles in the plays Electra, As You Like It, The Good Person of Szechwan (1990), and Machinal (1994) and received a further three Olivier Award nominations for her roles in Mephisto (1986), Hedda Gabler (1992), and Happy Days (2008). She made her Broadway debut playing the title role in Medea (2002), for which she earned a nomination for the Tony Award for Best Actress in a Play. She returned to Broadway in the Colm Tóibín play The Testament of Mary (2013).