This paper explores the imagined reindeer of the twentieth century. It examines the relationship between humans and the Arctic animal in a historical perspective and highlights five ways of imagining the reindeer. Over time, it was assigned the role of an exclusively Sámi animal and an unruly trespasser, but also turned into a modernization project before it became a vulnerable victim of toxicity, only to be reinvented as a harbinger of Sámi food sovereignty. Drawing from animal studies and using a range of archival material, I argue that each way of imagining the reindeer was followed by extensive policy and legal efforts in order to make the reindeer compliant and predictable. These efforts did not necessarily lead to the intended results, and hence the reindeer remained “unruly”. Analyzing the shifting meanings contributes to a better understanding of the history of the European Arctic from the vantage point of animal history.