This chapter takes a fresh look at the ideological and theological significance of the Mandylion of Edessa, an object of unparalleled importance for the religious identity of the Byzantines. Departing significantly from previous scholarship, it argues that the legend of the Mandylion is not about an especially authentic visual portrait of Christ’s face, but rather about Christ as the true image (eikon) of God the Father, understood in a purely ontological sense. Middle Byzantine theological writings about the Mandylion ought also to be read as late contributions to the debate on the legitimacy of visual representations of Christ.