The 4th century polymath Eusebius of Caesarea experimented with biography throughout his literary career. The Life of Constantine, his half-biography/half-panegyric chimaera, followed the Ecclesiastical History, a cross between biographical and national history, the collective biography The Martyrs of Palestine and the lost Life of Pamphilus, an idealised memorial of his mentor. This paper will use the last decade’s explosion of interest in Eusebius’ literary capacities to assess the changing portraits of Constantine in the Ecclesiastical History and the Life. In Books 9 and 10 of the Ecclesiastical History, largely complete by 316, Constantine is the climax of a work that presents the church to Eusebius’ audience of elite 4th century Christians as the locus of traditional Roman values. Constantine enters Rome in triumph as the ideal Roman general and bringer of stability after civil war. He is not the first Christian emperor (Philip the Arab and perhaps Tiberius precede him); he is the ideal Roman emperor, ideal because of his privileged relationship with the divine. He is a figure of hope come to fill a seat prepared for him through Books 1-8. The Life of Constantine, a new biography of a familiar subject, is a celebration of that hope realised over twenty years later. Eusebius is not longer holding aloft a “Great Imperial Hope” to convince an audience of the inevitability of Christianity’s inheritance of the Roman Empire. He is now constructing an ideal exemplar of a Christian emperor in action rather than in expectation.