Hannah Waddingham played Septa Unella on "Game of Thrones."Michael Buckner/Getty Images; HBOHannah Waddingham said that "Game of Thrones" left her with "chronic claustrophobia."Lena Headey's character Cersei repeatedly poured liquid on Waddingham's character Septa Unella's face.Headey previously told BI that Waddingham "was a trooper" while filming the scene.You might have heard Hannah Waddingham refer to filming her waterboarding scene in "Game of Thrones" as "the worst day" of her entire life.