This thesis investigates the contribution and significance in performance of supernumeraries in British court masques, 1594-1640. The six selected masques include a variety of performance venues and authors, with offerings by an assortment of monarchs (and others). There is also a range of performance dates between 1594 and 1640, including: a Scottish court masque and an Elizabethan court masque, two Jacobean masques, and two Caroline court masques, which were performed for or with a variety of monarchs or their consorts. The thesis is driven by practice-based research in relation to the venue, staging, costumes, props, lighting, and blocking with a view to determine the contribution and significance of these performers. Whilst mute roles are the focus of the analysis, this does not include either musicians or the main masquers. The investigation suggests the non-speaking supernumeraries were significant roles in performance and offered a contribution to the genre.