Nancy Wahinekapu Sumner (March 9, 1839 – January 10, 1895) was a high chiefess during the Kingdom of Hawaii of Hawaiian, Tahitian and English descent.

[1] She was the only child of William Keolaloa Kahānui Sumner, a hapa-haole (part Caucasian) Hawaiian high chief, and Manaiʻula Tehuiariʻi, a Tahitian princess and relative of the Pōmare Dynasty of Tahiti.

[3] Her paternal grandparents were High Chiefess Keakuaaihue Kanealai Hua and the British Captain William Sumner (1786–1847), of Northampton.

Her classmates included Princess Victoria Kamāmalu, the future Queen Liliuokalani and other members of the Hawaiian nobility.

In 1865, she met and befriended the Anglo-Irish aristocrat Lord Charles Beresford, R.N., while he was a midshipman on board the steam-corvette HMS Clio.

Her husband possessed no wealth and was of low genealogical rank, which prompted her father William K. K. Sumner to disinherit her and her descendants.