Katherine Elizabeth "Katie" McGrath (b. c. 1983) is an Irish actress and model. She is best known for playing Morgana in the BBC One television series Merlin, portraying Jules Daly in A Princess for Christmas, and appearing as Lucy Westenra on the British-American horror drama TV series Dracula in the autumn of 2013.

She appeared in Jurassic World (2015) as Zara Young, the assistant to Claire Dearing played by Bryce Dallas Howard. McGrath will costar in Knights of the Round Table: King Arthur coming out in 2016.

She is currently playing Lena Luthor in CW's show Supergirl starring alongside Melissa Benoist and Chyler Leigh. Lena Luthor is the adoptive sister of Lex Luthor but unlike Lex she is working with Supergirl rather than against.

She currently weighs 220 pounds.