McGrath was raised in Ashford, County Wicklow, by her father, Paul, who works with computers, and mother, Mary, who works for an Irish designer. She has two older brothers, Sean, an online media manager, and Rory, who is a post-production producer.[3] She studied the International Baccalaureate at St. Andrew's College before graduating from Trinity College, Dublin, with a degree in history with a focus on Russian history.[1]
At a young age she applied to the Ballygowan "Be the Face of MTV" competition.[4] Twenty finalists would be able to attend MTV Lick Party at the Tivoli.
Career
McGrath originally sought to work in fashion journalism and took on a job at Image magazine[1] before becoming a wardrobe assistant on the set of The Tudors. While working on The Tudors, McGrath was advised to try acting, so she sent photographs to Irish agents.[5] She said:
Being an actress was kind of like when you're a kid, and you want to run away and join the circus, it's something you really want to do, but then you grew up and got a proper job. It was a dream, but I didn't think it would ever be reality, and yet here I am![5]
McGrath was cast in Damage, an Irish TV-movie in 2007. She also starred in the play La Marea at the Dublin Theatre Festival in the same year.[6] She appeared in the feature films Eden and Freakdog in 2008, before being cast as Morgana Pendragon in Merlin.[7]
In 2011, McGrath appeared with Roger Moore in the comedy-drama film A Princess for Christmas, a Hallmark Channel Original Movie shot mainly at the Peleş Castle in Romania.[10] In September 2011, McGrath voice-acted the characters in the Irish animated short film Tríd an Stoirm (Through the Storm).[11] Later that month, McGrath was cast as Oriane Congost in Labyrinth.[12]
McGrath was reunited with her The Tudors co-star and close friend Jonathan Rhys Meyers in NBC and Sky Living's horror drama TV series Dracula; she portrayed Lucy Westenra.[13] In June 2013, McGrath co-starred in episode four of the Channel 4 show Dates as a young lesbian on the dating scene alongside Gemma Chan.[14]
In November 2014, McGrath co-starred in a Hozier music video for the song "From Eden".[15]
McGrath portrayed the lead role in the first season of Chiller's original horror series Slasher, which premiered on 4 March 2016.[18]
In 2016, it was announced that McGrath would play the recurring role of Lena Luthor in the second season of Supergirl.[19][20] She debuted in the season two premiere episode titled "The Adventures of Supergirl" and was promoted to a series regular in March 2017 and maintained this role until the show's end in 2021.[21][22] She appeared as Elsa in Guy Ritchie's fantasy film King Arthur: Legend of the Sword, which was released in May 2017.[23]
In 2019, McGrath starred alongside Abbie Cornish and Georgina Haig in Seven Network series Secret Bridesmaids' Business, about how a bride's wedding turns deadly after one of the bridesmaids invites a stranger into their lives. McGrath starred as Saskia, a bisexual lawyer who is described as an intelligent, loyal woman who is holding a secret.[24]
In September 2023, she had a supporting role in The Continental as the Adjudicator.[25]
