In the 1950s, she began appearing in movies as a character actress, such as her roles in "To Catch a Thief" (1955), and "North by Northwest" (1959), both starring Cary Grant and directed by Alfred Hitchcock. In "North by Northwest" she played Grant's character's mother, and in "To Catch a Thief" and "The Swan" (1956), she played the mother of characters played by Grace Kelly. Landis's appearance in "North by Northwest" earned her publicity for portraying Cary Grant's mother despite claiming to be nearly a year younger. Landis listed 1904 as the year of her birth. However, she had actually shaved eight years off her age. She appears in the 1900 U.S. Census as a 3-year-old born in November 1896; not old enough to be his (biological) mother.