Lord John Grey (1523/24 – 19 November 1564) was an English nobleman and courtier of the Tudor period, who after 1559 was seated at Pirgo Place in Essex. Lord John was at one stage sentenced to death for his involvement in Wyatt's Rebellion against Queen Mary I, but was later released from attainder. Grey was restored to his original position by Queen Mary's successor Queen Elizabeth I, who also granted him Pirgo Place in Essex as well as making him Guardian of Lady Katherine Grey, his niece, and sister of the late Lady Jane Grey, in 1563. However, Lord John was again imprisoned shortly before his death, after publishing a book asserting Katherine Grey to be the legitimate heir to the English throne.