William Marshall Cazalet DL JP (8 July 1865 – 22 October 1932) was a wealthy British landowner who represented Great Britain at the 1908 Olympic Games in jeu de paume (real tennis).

[2] His father had a real tennis court built for him at Fairlawne, the family home in Shipbourne, Kent.

[2] Cazalet represented Great Britain at the 1908 Olympic Games in jeu de paume.

[2][4] Cazalet was painted by John Singer Sargent in 1902, with his horse and wearing a hunting jacket.

[3][11] Cazalet's eldest son Edward, born 1894, was killed in action in France in 1916.