Baron Petre, of Writtle, in the County of Essex, is a title in the Peerage of England. It was created in 1603 for Sir John Petre. His family has since been associated with the county of Essex. He represented Essex in parliament and served as Lord Lieutenant of Essex. Lord Petre was the son of Sir William Petre, Secretary of State to Henry VIII, Mary I, Edward VI and Elizabeth I. Sir William acquired Ingatestone Hall and the surrounding manor from Henry for the full market value after it had been surrendered to the King by Barking Abbey during the Suppression of the Monasteries.

John Petre, 1st Baron Petre was an English peer who lived during the Tudor period and early Stuart period. He and his family were recusants — people who adhered to the Roman Catholic faith after the English Reformation. Nevertheless, Lord Petre was appointed to a number of official positions in the county of Essex.