Monsters, by the Latin definition of their name, are omens that portend turbulent times. The pamphlet A Relation of a terrible Monster called a Toad-fish, published in London in 1642, told of “a fiend, not a fish; at the least a monster, not an ordinary creature” which had become entangled in a fishing net and then put on display in London. The creature was described as resembling a giant toad, with a wide, toothy mouth and human characteristics of ribs, hands, and fingers. Discovery of the Thames monster instilled a sense of worry throughout the realm. The landing of the “Toad-fish” was linked in the tract to a bloody encounter that occurred between two well-known members of the British aristocracy fighting on opposing sides at the onset of the Civil War. The present paper describes how this vernacular publication was part of a flourishing of providential pamphlets in the 17th century wherein natural anomalies were invested with wider ecclesiastical and political meaning. Also undertaken herein is a review of various candidate species from which to suggest that the mysterious Toad-fish may have been another example of the angelshark’s (Squatina squatina) monstrous alter ego. This is an animal that has previously been suggested as being responsible for the ‘sea monk’ noted in several prominent natural histories of the Renaissance.