The Hellmouth is an entrance to hell that manifests as the open jaws of an infernal beast. Depictions of Hellmouths were common during the Middle Ages and Renaissance in manuscripts, and even as dramatic mechanical set pieces in theatrical productions.
Detail of The Mouth of Hell, from the Book of Hours of Catherine of Cleves, 1440
Vision de l’Enfer (Vision of Hell), from Les Visions du chevalier Tondal, 1475
Ludolf of Saxony, Inferno, from Speculum Humanae Salvationis, 1455
Lambert of Saint-Omer, Liber Floridu, 1250 – 1275
Detail of Jugement Dernier – Damnés (Last Judgement – The Damned Souls), 1492
The Monster of Krakow first appeared in Histoires Prodigieuses by Pierre Boaistuau, 1559. Four hours after its birth, the demonic beast reportedly uttered “Watch, the Lord cometh” and died. Source: Wellcome Collection