Elaine Cassidy (born 31 December 1979)^[1] is an Irish actress. Her acting credits include The Sun, the Moon and the Stars (1996), Felicia's Journey (1999), The Others (2001), Disco Pigs (2002), The Ghost Squad (2005), Fingersmith (2005), And When Did You Last See Your Father? (2007), Harper's Island (2009), Little White Lie (2011), The Paradise (2012), The Program (2015), No Offence (2015–2018), Strangeways Here We Come (2018), A Discovery of Witches (2020), Intruder (TV series) (2021), The Wonder (2022), and The Last Kingdom: Seven Kings Must Die (2023).

Cassidy was born in Raheny, and moved with her family to Kilcoole when she was three years old.^[1] Her first role was as the title character in a school production of Pinocchio when she was five.^[1] She participated in drama classes throughout secondary school.^[2]

In 1996, Cassidy was nominated for the Most Promising Actress at the Geneva Film Festival for her role in The Sun, the Moon and the Stars.^[3] In 1999, she played the starring role in Felicia's Journey, for which she was nominated Best Actress at the 20th Genie Awards.^[1] She was named EFP European Shooting Star for in 2001.^[3]

She has won 2 Irish Film and Television Awards (IFTA) for Best Actress in a Lead Role in Film in 2003 for her role as Runt in Disco Pigs, and in 2010 for Best Actress in a Lead Role in Television for her role as Abby Mills in the American CBS TV series Harper's Island.^[4] She was also nominated for an IFTA in 2005 as Best Actress in a Lead Role in Television for her role as "Maud Lilly" in the BBC BAFTA nominated drama Fingersmith,^[1] in 2007 as Best Actress in a Supporting Role in Film for her role as Sandra in And When Did You Last See Your Father?, and in 2009 as Best Actress in a Lead Role in Television for her role as Annie Mulcahy in Little White Lie.

In theatre, she has appeared in The Lieutenant of Inishmore (2002) and The Crucible (2006) with the Royal Shakespeare Company, and in There Came A Gypsy Riding at the Almeida Theatre in 2007.^[5]

In 2008, she appeared in the music video for Coldplay's "The Scientist".^[6] In 2011, she played Maureen in the TV movie Just Henry.

In 2015, she played a main role of DC Dinah Kowalska in the Channel 4 drama series No Offence (2015–2018),^[2] and Sarah Manning in Acceptable Risk (2017).^[7]

In 2022, she starred as Rosaleen O'Donnell in the Irish film The Wonder, alongside her own daughter Kila, who played "the wonder" and co-starring Florence Pugh.^[8] She received a nomination for Best Supporting Actress in a Film at the 'Irish Film and Television Awards in 2023.^[9]

In 2023, she starred in the film The Last Kingdom: Seven Kings Must Die, playing Eadgifu of Kent, the role was previously played by Sonya Cassidy in the TV series.^[10]

Cassidy married English actor Stephen Lord, whom she met on the set of The Truth, on 31 December 2007. They live in Greenwich, London, with their daughter Kila (born 16 September 2009)^[11] and son Lynott Lord Cassidy (born c. 23 January 2013).^[2]

• The Lieutenant of Inishmore (2002)
• Scenes from the Big Picture (2003)
• The Crucible (2006)
• There Came a Gypsy Riding (2007)
• Fathers and Sons (2014)
• Deluge (2015)
• Les Liaisons Dangereuses (2015 to 2016)
• Aristocrats (2018)