This paper calls attention to an important, yet neglected, subset of medieval Latin sources: the dozens upon dozens of works of late antique and early Byzantine Christian Greek authors translated into Latin between the second and thirteenth centuries. It also introduces a new initiative to study these sources: "The Lost Patriarchs Project." After considering some examples of medieval Latin texts with Greek origins across a number of genres and the reasons why these texts have not been the subject of critical inquiry, this paper announces the plans for a new instrument of reference to study the dissemination and impact of Greek patristics in Latin translation: The Lost Patriarchs: A Survey of the Greek Fathers in the Medieval Latin Tradition.