Lady Jane Grey, formally Jane of England (1537 — 12 February 1554), a grand-niece of Henry VIII of England, reigned as uncrowned Queen regnant of the Kingdom of England for nine days in July 1553.
Though Jane's accession, pursuant to the Will of King Edward VI, may have breached the laws of England, many powers of the land proved willing to accept her as Queen of England, even if only as part of a power-struggle to stop Henry's elder daughter, Princess Mary, a Roman Catholic, from acceding to the throne. Jane's brief rule ended, however, when the authorities revoked her proclamation as Queen. Mary's subsequent régime eventually had her executed for treason.
Popular history sometimes refers to Lady Jane as "The Nine Days' Queen" (10 July — 19 July 1553) or, less commonly, as "The Thirteen Days' Queen" (6 July — 19 July 1553) — owing to uncertainties as to when she succeeded to the throne. Historians have taken either the day of her predecessor's death (July 6) or that of her official proclamation as Queen (10 July), as the beginning of her short reign.
Lady Jane had a reputation as one of the most learned women of her day, and the historical writer Alison Weir describes her as one of "the finest female minds of the century".