Sir Henry Paulet St John-Mildmay, 6th Baronet JP (28 April 1853 — 24 April 1916) was an English first-class cricketer and British Army officer.

The son of Sir Henry St John-Mildmay, 5th Baronet and his wife, Helena Shaw Lefevre, he was born at Westminster in April 1853. Mildmay was educated at Eton College,^[1] before joining the Grenadier Guards as a sub-lieutenant. He was promoted to lieutenant in July 1874.^[2] Mildmay, who played services cricket for the Household Brigade,^[3] made his debut in first-class cricket for Hampshire against Sussex at Hove in 1881. He made three further three appearances for Hampshire in that season, followed by a further appearance in May 1882.^[4] His participation in the 1882 season was likely cut-short by his service in the Anglo-Egyptian War of July—September 1882, in which he gained the Khedive's Star.^[1] Returning to England following the conflict, Mildmay made two further first-class appearances for Hampshire, against Sussex in 1883 and Kent in 1884.^[4] Described by Wisden as "a good, steady bat and safe field",^[3] he scored 137 runs at an average of 11.41, with a highest score of 26.^[5]

In the Grenadier Guards, he was promoted to captain in July 1884.^[6] In 1885, he saw action in the Mahdist War, partaking in the Nile Expedition to relieve Khartoum and was mentioned in dispatches.^[1][7] Mildmay was promoted to brevet major in August 1885,^[8] and later retired from active service in June 1894.^[9] Mildmay succeeded his father as the 6th Baronet of the St John-Mildmay baronets upon his death 1902.^[10] He later served as a justice of the peace for Hampshire.^[1] Mildmay died in April 1916 at Dogmersfield Park in Dogmersfield, Hampshire.^[10] Having died without issue, he was succeeded as the 7th Baronet by his younger brother, Sir Gerald St John-Mildmay.