Joseph P. Kennedy, Sr.
Kathleen Agnes Cavendish, Marchioness of Hartington (; February 20, 1920 – May 13, 1948), also known as "Kick" Kennedy, was an American socialite. She was the second daughter of Joseph P. Kennedy, Sr. and Rose Kennedy as well as a sister of former U.S. President John F. Kennedy and Senators Robert F. Kennedy and Edward M. "Ted" Kennedy and the wife of the Marquess of Hartington, heir apparent to the 10th Duke of Devonshire.