This paper describes the self-concept of Bernard Gui as an inquisitor in the Middle Age and compares this with the perception and the presentation by people and groups from other eras. Therefore, the underlying tensions are revealed and causes behind the transformations are reflected. Guis function as inquisitor was part of an interplay between different social, political and religious structures in the “Ketzernest” Toulouse and the general situation of the church in the 14th century. What Gui thought about his own work and why he imagined himself as a seelenarzt and defender of faith can be seen in his handbook Practica (officii) inquisitioinis haereticae pravitatis, which the Dominican wrote as a tool for other inquisitors. In addition, the paper reports the history of reception and explains the transformation in this. Consequently, this paper describes how different people at diverse times and various places thought about Gui and refers to the setting and the ideas on those times. Hence, statements of Bernard Deliceux, a critical Franciscan of his time, the results from the ancient research, the representation Gui in the historical novel Der Name der Rose by Umberto Eco and the film The Name of the Rose by Jean-Jacques Annaud are analyzed. These images are scrutinized with regards to the consequences for the collective memory and are confronted with results from the recent research. Furthermore, the paper states reasons how Bernard Gui can be judged in a historical perspective.