Mary Carolyn Campbell McCreery (née Cuyler, formerly Lady Grey-Egerton) (23 December 1871 – 25 November 1958) was an American socialite.
 May was born on 23 December 1871 in Milwaukee, Wisconsin. She was a daughter of Alice (née Holden) Cuyler and Maj. James Wayne Cuyler (1841–1883) of Baltimore, Maryland. Her father, a West Point graduate and engineer, fought for the Union Army in the U.S. Civil War.
 Her paternal grandparents were physician and Bvt. Brig.-Gen. John Meck Cuyler (son of Judge Jeremiah La Touche Cuyler) and Mary Campbell (née Wayne) Cuyler (a daughter of Associate Justice of the Supreme Court of the United States James Moore Wayne). A first cousin of her grandfather was U.S. Representative Rudolph Bunner. Her maternal grandparents were Wisconsin State Assemblyman and avid abolitionist Edward Dwight Holton and Lucinda Caroline (née Millard) Holton (a second cousin of Millard Fillmore). Her aunt, Mary Holton, married Robertson James, the youngest brother of novelist Henry James.
 On 4 January 1893, May was married to Sir Philip Grey Egerton, 12th Baronet in London. Sir Philip was the only son of Sir Philip Grey-Egerton, 11th Baronet and Hon. Henrietta Denison (eldest daughter of Albert Denison, 1st Baron Londesborough). Their engagement had been announced in The New York Times on 29 October 1892, and the "wedding received extensive press coverage, featuring lists of the jewels received as gifts, including a diamond tiara." After their marriage, "she became as great a belle in London society as she had been" in the United States. Before their divorce in May 1905, they were the parents of twin sons and a daughter:
 After their divorce, May married Richard Stephen McCreery (1866–1938) on 2 March 1907 at May's residence on Hallam Street in London. McCreery, who was divorced from Edith Kip, was a son of Andrew Buchanan McCreery and Isabel (née Swearingen) McCreery. His maternal aunt, Mary Swearingen, was the wife of Supreme Court Justice Stephen Johnson Field, and his nephew was Gen. Sir Richard McCreery, Commander of the British Eighth Army. With her second husband, she was the mother of:
 Her first husband, Sir Philip, died on 4 July 1937, and her second husband died in 1938. As both of their sons predeceased their father, the baronetcy passed to the Rev. Sir Brooke de Malpas Egerton, Sir Philip's first cousin once removed. May died at her home, 2202 Forest Drive in Burlingame, California on 25 November 1958.
 Through her daughter Cecily, she was a grandmother to three: Cynthia Mary Denise Prideaux-Brune (b. 1919), Philip Egerton Edmund Prideaux-Brune (b. 1921), and Rowland Denys Charles Prideaux-Brune (1925–2008).
 During the 2014 to 2015 exhibition at London's National Portrait Gallery, May was featured among the high-profile American heiresses to marry into British aristocracy. Included in the exhibition were Jeanette ('Jennie') Churchill (née Jerome), Lady Randolph Churchill, Mary Victoria (née Leiter), Lady Curzon of Kedleston, Cornelia Craven (née Martin), Countess of Craven, Consuelo Montagu, Duchess of Manchester, Consuelo (née Vanderbilt), Duchess of Marlborough (later Mrs. Balsan), John Spencer-Churchill, 10th Duke of Marlborough, Lord Ivor Spencer-Churchill, Marguerite Hyde ('Daisy', née Leiter), Countess of Suffolk.