Kathryn Crosby (born November 25, 1933) is a retired American actress and singer who performed in films under the stage-names Kathryn Grant and Kathryn Grandstaff.
Born Olive Kathryn Grandstaff in Houston, Texas, she graduated from the University of Texas at Austin with a Bachelor of Fine Arts in 1955. Two years later she became Bing Crosby's second wife, being more than thirty years his junior. The couple had three children, Harry, Mary Frances, and Nathaniel. She appeared as a guest star on her husband's 1964–1965 ABC sitcom The Bing Crosby Show.
She largely retired after their marriage, but did have a featured role in the courtroom drama Anatomy of a Murder (1959). She also played the part of "Mama Bear" alongside her husband and children in Goldilocks and co-starred with Jack Lemmon in the comedy Operation Mad Ball (1957), with Tony Curtis in the drama Mister Cory (1957) and as a trapeze artist in The Big Circus (1959).