This paper attempts to illuminate the ways in which the anxiety of the imperial subject in the Romantic period gets translated into gender anxiety in Robert Southey’s Thalaba the Destroyer. Critics who work on Romantic colonial discourse have emphasized that contemporary texts dealing with the unknown world are saturated with unexpected instability. As the newly discovered space is frequently gendered feminine in colonial discourse, this instability often goes hand in hand with masculine anxiety about the female in the unknown world. The narrative of Thalaba the Destroyer relies on the sympathy between its hero and readers, especially because Thalaba resembles the traditional protagonist in the medieval romance, whose fierce fights with the evil elements result ultimately in the possession of his desired woman. Yet, despite the apparent similarity, Southey deploys the generic conventions of the medieval romance only to frustrate the readerly expectation. The marriage between Thalaba and his beloved Oneiza leads to the abruptly introduced death of the bride. Along with Southey’s depiction of Oneiza as an active agent of both her own life and narrative progress, her unexpected demise points to the hero’s failure to establish a stable relationship with the heroine in the realm of the text. Instead, the failure of romance indicates the fact that the reunion between Thalaba and Oneiza is deferred beyond the domain of narrative. Moreover, Oneiza re-appears in the text in the form of a vampire, causing an abrupt change in the progress of narrative and an enormous distress in Thalaba’spsyche. The vampire woman, whose depiction highlights its difference from human beings, embodies the threat posed by the foreignness of the female in the unknown world. Also, the vampire disrupts the traditional male/female opposition, as its mouth simultaneously plays the function of the penetrating and the receptacle. In this sense, the corrective penetration performed by Moath, Oneiza’s father, appears to recover the order of patriarchy. Yet, Thalaba’s inability to take part in the murder of the vampire denotes his lack of control over his own married wife, revealing the limit of the patriarchal order established by the elimination of the vampire. Thalaba also encounters Maimuna, a sorceress disguised in the form of a beautiful damsel, and her slender golden thread arouses the hero’s desire. Yet, the thread ultimately ensnares Thalaba, conveying the uncomfortable message that materialistic desire may lead to the destruction of the imperial subject.