The present paper examines the topic of aliases of criminals, which seems to be understudied in linguistic research. Therefore, this article's primary goal is to describe how criminals' aliases are created and what are the differences and similarities in that process in English, French, and Polish. Firstly, the theoretical background concerning the topic of pseudonyms is presented. Then, the corpus gathered for this paper (available online: https://cutt. ly/1TRefrK), consisting of 206 pseudonyms (123 units in English, 42 in French, and 41 in Polish), is analyzed. In the analysis, four schemes are noted to be the most commonly used in creating pseudonyms of criminals. What is more, the inspirations behind the creation of criminals' pseudonyms are scrutinized, and nine typical inspirations are distinguished. The article constitutes not only a detailed linguistic analysis of a significant number of criminals' aliases but can also serve as an inspiration for other research on the topic.