Depictions of lions have been used since the Stone Age as apotropaic guardians at entrances. According to research, lion heads as sculptural decorations of portals have been found since the 4th century BC. In that period, they were documented in the area of Southeast Europe, and until the end of Late Antiquity, we find them on tombs, temples, sarcophagi, and some churches. The last late antique example dates from the 4th century AD. After that, the first lion's heads are used again on the Palatine Chapel in Aachen. The beginnings of their appearance in the early Middle Ages are connected with the development of artistic production during the Carolingian period, which primarily relied on ancient and early Christian traditions. It has not been fully revealed whether the lion's heads were used only as a way of preserving that tradition as prescribed in the Liber Carolina, and therefore only their form was adopted, or whether the symbolism of the lion itself played a role in their selection. In this thesis, the significance of lion heads in the context of the iconographic programs of medieval portals is examined based on the catalog of all found lion heads on the doorposts of churches from the territory of today's Germany from the 9th to the 12th century. The paper questions the symbolic role of lion heads and draws conclusions about their significance. It also provides an overview of the development of the forms of lion heads, discusses the challenges in categorizing them, and suggests potential avenues for future research. The collected information is visualized with the help of pictorial examples and five maps created for display purposes. One of the maps integrates all the found examples with the centers of medieval power in the territory of Germany, while the others visualize the found examples in certain time periods.