Lady Jane Grey, (1536/1537–12 February 1554), also referred to as Queen Jane, a greatniece of Henry VIII of England, was a claimant to the Kingdom of England and Kingdom of Ireland. Her claimed rule of nine days in July 1553 is the shortest rule of England in its history.
Jane's accession, pursuant to the will of Edward VI, breached the laws of England as under the Third Succession Act, Mary Tudor, Henry VIII's eldest daughter, was the legitimate and rightful heir to the Crown. However, Mary had been declared illegitimate by her father, and the same ruling had been applied to her younger half-sister, Elizabeth, later Elizabeth I. (This declaration of illegitimacy was made to keep Mary, a Catholic, from receiving the crown, which Henry VIII had for a time wished to keep in Protestant hands.) Their positions in the line of succession had, however, been restored by the Third Act of Succession.
Nevertheless, many high-ranking nobles proved themselves pliable to having Jane as Queen of England. Acting largely out of financial self-interest, they supported her even if only as part of a power struggle to keep Henry's first-born, the staunchly Catholic Mary, from ascending the throne. Jane's rule ended quickly when the nobles abandoned their support once they realised Mary had won the day. Mary pardoned Jane; however after a subsequent attempt by her supporters to seize the crown, Mary had her executed for high treason.