William Flower (1497/98–1588) was an English Officer of Arms in the reigns of Henry VIII, Edward VI, Mary I and Elizabeth I. He rose to the rank of Norroy King of Arms, serving in that capacity from 1562 until his death in 1588.
William Flower was born at York about 1498, and was probably the elder son of John Flower, tailor and corn merchant, of the parish of All Saints' Church, Pavement, York. Flower became Guisnes pursuivant extraordinary on the removal of Fulke ap Howell at Westminster, 10 June 1536. On 1 April 1543, while serving as Calais pursuivant extraordinary, he was sent to visit the merchants and marines who had been captured by the French and confined at Rouen. He was appointed Rouge Croix Pursuivant in 1544 and Chester Herald of Arms in 1546. He and Gilbert Dethick, Garter Principal King of Arms accompanied William Parr, 1st Marquess of Northampton, in his 1551 mission to Paris, to invest Henry II of France with the Order of the Garter. He received ten shillings per day for his "dyett" (food and lodging) on that mission. In 1555, Thomas Hawley, Clarenceux King of Arms, issued a patent in London authorising Flower to act as his marshal and deputy. Flower delivered a message in Edinburgh from the Duke of Norfolk on 16 February 1560 to Mary of Guise and her Scottish and French councillors. At first they spoke in the "Scottish tongue" but because he could not understand they continued in French. Flower recorded sharp answers from two Frenchmen, Henri Cleutin and Jacques de la Brosse.