This paper aims to provide the first comprehensive evaluation of Carl Gustav Carus's writings on race and human inequality. We demonstrate that Carus, an eminent nineteenth-century physician emblematic of romantic medicine, was deeply engrossed in racial science, exploring anatomical, anthropological, and craniological dimensions of race across no less than twenty-five works spanning three decades. Carus's engagement with race stemmed from naturphilosophisch anatomical and physiological considerations, which evolved into physiognomic and psychological inquiries. While previous research has construed Carus as a precursor of Arthur de Gobineau, we argue that he was intellectually much more closely aligned with the 'American School' of ethnology, represented by figures such as Samuel G. Morton, George R. Gliddon, and Josiah C. Nott. Closely monitoring international discourses of scientific racism, Carus sought to propagate these notions among German readers and position himself within international debates. The international reception, however, was limited by the Romantic framework of Carus's scientific racism, which was unintelligible to contemporaries. While sharing an implicit methodological bias with Morton and his followers, affirming white superiority and legitimising colonisation, the Romantic underpinning of his race treatises made it difficult for mid-nineteenth-century race theorists to fully endorse him. Nonetheless, Carus, often lauded as polymath with a humanistic orientation, besides his achievements, helped to create a theoretical basis for the othering and dehumanisation of large parts of the global population.