This paper analyzes the theory of the Great Replacement, a concept first popularized in France and later expanded to the European and global levels. Throughout the work, special focus is placed on understanding how this theory fits into the identity discourse of the Croatian right-wing and how Croatian right-wing political actors use the theory. In particular, the paper offers a comprehensive insight into the evolution of the Great Replacement theory, from its begining to its spread on the international scene, with an emphasis on the role of mass migration. Within the Croatian political scene, the study explores how the theory of the Great Replacement is used in the rhetoric of right-wing political actors, especially on social media, and by using qualitative analysis of documents and content on platforms like TikTok, Facebook, and Telegram, the paper identifies the main patterns of discourse that link migration with the perception of a threatened national identity. Although the theory has garnered some support and continues to be part of the right-wing discourse in Croatia, the analysis of comments reveals that public reactions vary, with criticism of the actors prevailing and clear skepticism about the theory itself. The content on the social media platforms of certain right-wing political figures aligns, to some extent, with a conspiratorial form of spreading the Great Replacement theory, inciting fear of migrants and invoking the main conspiratorial element of a “secret plan.” Additionally, topics such as migration and demographic changes are frequently associated with the Great Replacement theory, thereby giving it a conspiratorial meaning. The paper concludes by highlighting the potential use of the Great Replacement theory as a tool for shaping narratives about identity and national security and shows how it has been portrayed in contemporary political discussions. This research provides a foundation for further analysis, especially in the context of the increasing influx of foreign workers and potential social tensions in Croatia.