This communication will examine how an enduring tradition of pictorial representation of demoniac bodies, coming from paintings, engravings and architectural reliefs, back to medieval ages up to romantic aesthetics in the XIXth century, has directly influenced the medical gaze and its use of photography, and instilled the concept of objectivity. This concept has emerged contesting mythology and the imagination. However, we will show how imagination was not, in fact, dismissed and played an important part of knowledge construction of all times. We will take into consideration some photographic examples of the portuguese medical photography collected by our research project on the Visual Culture History of Portuguese Medical Images and look at it through this demoniac tradition. Some of these images are also connected with colonial medical photography and its representation of black people.