Trivia

She is a huge sci-fi and fantasy fan and collects Star Wars figures.

Worked several jobs prior to becoming an actress: at a piercing studio, in a cocktail bar, as a make-up artist for MAC cosmetics, worked for Image magazine, and as a wardrobe assistant on Les Tudors (2007).

She did all of her own stunts in Jurassic World (2015). The director, Colin Trevorrow, said, "I just think it's the most epic Jurassic Park death I could possibly imagine.".

She uses her natural Irish accent in the series Merlin (2008), while her co-star, Irish actor Colin Morgan fakes an English accent. Katie almost didn't get her role because "Merlin" producers didn't want two actors speaking with an Irish accent in the series, and they were ready to reject her for a role if she couldn't sound English, that is if Colin couldn't nail the English accent first.

Compared to most aspiring actors, getting a job as an actress happened quickly for her. She made her on-screen debut in Damage (2007). Later that year, she was able to get an agent by October 2007 when one of the Les Tudors (2007) crew drivers gave her a confidential cast list with all the actors' agents' details on it; a few months later, in January 2008, she read for Merlin (2008) and became a series regular.

The only leading cast mate in Merlin (2008) who is not a formally trained actor.

Became disinterested with her fashion job at Image magazine after eight months. Her mother's best friend, one of the top first-assistant directors in Ireland, had been working on Les Tudors (2007) and gave Katie a job in the show's costume department because of her prior experience working in fashion; however, Katie didn't know how to sew and had no knowledge or experience in costume design.

She is a big fan of Harrison Ford and Nathan Fillion.

She loves comic books.

McGrath studied the International Baccalaureate at St. Andrews College before graduating from Trinity College, Dublin with a degree in History.

She played the younger sister of Emilia Fox in both Merlin (2008) and The Queen (2009).

Revealed she never aspired to becoming an actress. She had no formal acting training outside of performing in school plays and did not attend drama school. She had been working as a wardrobe assistant on Les Tudors (2007) when a couple of the show's producers and directors suggest she try acting. She wasn't interested, until she saw how more relaxed the actresses' jobs were on the set compared to her job working hard, long hours on costumes as a wardrobe assistant. This prompted her to take up acting and she made her on-screen debut in Damage (2007). She later convinced the director of Les Tudors (2007) to give her a part in the series.

Friends with Colin Morgan and Jonathan Rhys Meyers.

Has a tattoo on her back that says 'Purity'.

Her last name is pronounced "Mc-Grah".

Friends with Natalie Dormer.

Appears in both medias based on the Arthurian legends with the TV series Merlin (2008) as Morgana Pendragon and the movie Le Roi Arthur : La Légende d'Excalibur (2017) as Elsa.

Her brother Sean did the visual effects for Captain America: Civil War (2016).

Worked under costume designer Joan Bergin on the set of Les Tudors (2007).

Has two older brothers, Sean, an online media manager, and Rory, who is a post-production producer.

Parents are Paul, who works with computers, and Mary, who works for an Irish designer.

Her great-grandfather was Joseph McGrath who was a politician in Ireland.

Katie McGrath did all of her own stunts in Jurassic World (2015).