The tomb of Mary Queen of Scots is widely recognized as one of the most important visual symbols of dynastic power that can still be viewed in Britain today. Although art historians had originally regarded the strongly Catholic depiction of Mary in captivity, the so-called Sheffield portrait, as the model for the effigy, for more than a century the consensus is that it was based on one of Nicholas Hilliard’s miniature portraits. In this essay a study of the images as well as related documents in the exchequer and Hardwick Hall accounts reestablishes that the Sheffield type was indeed the specific model for the tomb. This does more than simply settle a long-standing question. It also opens the way for an exploration of the content of this most popular portrait of Mary, which was fraught with significance not only for King James VI, Mary’s son, but also the crypto-Catholic nobleman Henry Howard, first earl of Northampton, who was in charge of the tomb’s completion.