Theatrical masks in portraits of eighteenth-century actresses signify more than the figure’s profession. Multiple masks in a single composition and the figure’s active engagement with these plastic, yet eerily human objects suggest a more complex relationship between the theatrical mask and portraiture. Many scholars have examined eighteenth-century British actress portraits as tools by which the sitter elevated her reputation and distanced herself from associations with prostitution. Yet the presence of the theatrical mask in portraits by Joshua Reynolds, John Hoppner, and William Beechey, for example, has received no critical attention. Quantity, placement, and interaction between actress and object indicate metaphorical significance and demand examination. I argue the mask acts as a marker of duality and potential deception, becoming the locus for anxieties within the sister arts of theatre and painting. Artistic and dramatic theorists were in the process of codifying each medium based upon strict categories and dichotomies. Yet the actress’s proclivity for deception spilled onto the canvas, requiring artistic intervention. As such, the mask was a site of artistic and social anxiety, where gender norms, aesthetic principles, and power relations were visually negotiated.