Life of Constantine the Great is a panegyric written in Greek in honor of Constantine the Great by Eusebius of Caesarea in the 4th century AD. It was never completed due to the death of Eusebius in 339. The work provides scholars with one of the most comprehensive sources for the religious policies of Constantine's reign. In addition to detailing the religious policies of the Roman Empire under Constantine, Eusebius uses Life of Constantine to engage several of his own religious concerns, such as apologetics, as well as a semi-bibliographic account of Constantine.

Constantine I, also known as Constantine the Great, was a Roman emperor from AD 306 to 337 and the first Roman emperor to convert to Christianity. He played a pivotal role in elevating the status of Christianity in Rome, decriminalizing Christian practice and ceasing Christian persecution in a period referred to as the Constantinian shift. This initiated the cessation of the established ancient Roman religion. Constantine is also the originator of the religiopolitical ideology known as Constantinism, which epitomizes the unity of church and state, as opposed to separation of church and state. He founded the city of Constantinople and made it the capital of the Empire, which remained so for over a millenium.