Among the most successful and long-lasting of Christian literary genres to emerge in late Antiquity was the passio (or acta or gesta) narrating a martyr's arrest, interrogation, suffering and execution. A handful of such works – including the Passions of St Perpetua and St Felicity, Bishop Polycarp, and the Martyrs of Lyon, along with the so-called Proconsular Acts of St Cyprian, to name the best known – are believed to have been composed during the age of persecution itself, the first three centuries ad, by eye-witnesses or by others with access to trial records. These few early passiones form a special category of the genre, labelled ‘passions historiques’ by their pre-eminent modern critic, the Bollandist Hippolyte Delehaye. After official persecution ended, and especially with the promotion of the cult of martyrs and their relics in the fourth and fifth centuries, dozens of other martyrs' passiones were composed in Greek or Latin in various parts of the Christian Empire. Some of the Greek passions, in Latin translation, and many of the Latin passions originating in Rome itself, became popular in religious communities across Europe in the early Middle Ages and later, to judge from the surviving martyrologies and the abundant manuscript remains of the passiones themselves.

While the so-called historical martyrs' passions have been edited and studied frequently in the modern era, historians and philologists have mainly ignored the later passiones, which Delehaye and Aigrain have labeled ‘les passions épiques’ and ‘passions romanesques’, with their more sensational, miracle-filled and typically ‘hagiographical’ content; and because they are presumed to be largely forgeries and fiction, except for the names of the martyrs themselves (and not all of these are genuine).