Mary Wolverston, Lady Killigrew (formerly Knyvett; born before 1525 – died after 1587), was a gentlewoman from Suffolk, married into an ancient Cornish family, who was accused of piracy during the reign of Queen Elizabeth I (1558-1603).

Several sources have confused this lady with her husband Sir John IV Killigrew's mother, Elizabeth Trewennard/Trewinnard, and even with his granddaughter-in-law, Jane Fermor.

She was the daughter of Philip Wolverston (often described as a "gentleman pirate") of Woolverstone Hall in Suffolk, and widow of Henry Knyvett.

She was the wife of Sir John IV Killigrew of Arwenack (d. 1584), near Penryn in Cornwall, 2nd Governor of nearby Pendennis Castle, built on the family's estate.

He was MP for Lostwithiel in 1563 and twice for the family's pocket borough of Penryn, in 1571 and 1572.

In the 1540s, Pendennis Castle was built by King Henry VIII on part of the Arwenack estate belonging to the Killigrew family. Mary's father-in-law John III Killigrew (d. 1567) was appointed by the king as the first hereditary Governor of Pendennis Castle, and after his death Queen Elizabeth I appointed, as second Governor, his son, Sir John IV Killigrew.

The Governorship allowed control to be exerted on all of the shipping in the Carrick Roads harbour (the third largest natural harbour in the world), and along part of the south coast. Sir John IV Killigrew used his privileged position to prey on the cargoes of the ships that came within his reach. In 1567 Arwenack House was fortified as a stronghold and used to store merchandise stolen in raids on ships. Mary and her husband paid large fees to officials, bribing them to allow their illicit activities. Mary played an active role in the piracy, and apparently enjoyed the adventure more than her husband.

Historian Neville Williams described Mary (whom he erroneously called "Elizabeth") as a "tough and unprincipled businesswoman" who managed Arwenack House and oversaw the burial of treasure in her garden.