Catherine McCormack

McCormack was born in Epsom, Surrey, England. One of her grandfathers was Irish. Her mother died of lupus when McCormack was six years old and her steelworker father subsequently raised her and her brother Stephen. She was brought up as Roman Catholic and attended the Convent of Our Lady of Providence. She went on to study at the Oxford School of Drama.

McCormack has shown a preference in her career for the theatre, saying that "theatre really is an actor's medium: you're on stage with no director anymore, whereas in film very rarely do you get much rehearsal other than running through the scene very quickly. Then everyone comes in and shoots it." McCormack was one of the original 2006 London cast of Patrick Barlow's play of The 39 Steps. In 2008, she performed the role of Nora in A Doll's House, directed by Peter Hall at the Theatre Royal, Bath, and also the role of Isabel Archer in a stage adaptation of The Portrait of a Lady, both of which commenced their runs in July 2008, ending in August, before transferring to the Rose Theatre in Kingston later that year. In 2009, she appeared in the British tour of Headlong's adaptation of Six Characters in Search of an Author. In 2012, she starred as Juana Inés de la Cruz in the Royal Shakespeare Company's production of Helen Edmundson's play The Heresy of Love.

As of 2009, McCormack was living with her boyfriend in Richmond.