Kevin Spacey as Frank Underwood. Francis J. Frank Underwood is a fictional character and the protagonist of the American version of House of Cards. He is portrayed by Kevin Spacey. He is a variation of Francis Urquhart, the protagonist of the British novel and television series House of Cards, from which the American Netflix series is adapted. He is married to Claire Underwood (Robin Wright), but also had a sexual relationship with Zoe Barnes (Kate Mara) in season 1.