The purpose of this paper is to prove that the marvelous phenomena described in the works of Gerald of Wales and Walter Map played a double, religious and political role. This twofold role of mirabilia resulted from the ambiguous position of courtier clerics, who seemed to exist on the borderline between the religious and secular sphere. Both, Gerald of Wales and Walter Map, were archdeacons and strove to obtain episcopal nominations. However, in addition to being clergymen, they pursued a secular career on the royal court. As a result, they wrote texts in which they used various strategies to convey a religious, Christian perspective and to secure political interests of the House of Anjou. Mirabilia proved to be a useful tool helping them to achieve both aims. Thus, they strove to rewrite old, pagan stories of werewolves, vampires or revenants from the standpoint of the Catholic religion, adapting them to the official doctrine, or at least weakening their subversive character. However, apart from the religious role of marvels, their political function seems to be equally significant. They served as a useful tool for political propaganda: for legitimization of the rule of the new Plantagenet dynasty and justification of conquest of new territories. Finally, the inclusion of wonders from the Celtic “fringes of the world”, that is from Wales and Ireland, into courtly texts tied those territories more closely to the Angevin Empire.