The representation of the Catholic Monarchs, Ferdinand and Isabella, on the Golden Age stage has been somewhat neglected in recent scholarship. Despite a growing interest in the critical potential of portraying monarchs in the theatre and a recent monograph on the character of Isabella in the Golden Age theatre (María Y. Caba), the only study dedicated to the royal couple in the drama of the period (DeLys Ostlund) concludes that their portrayal is largely conformist and laudatory of their role in the unification of Spain. This article, which draws on the above scholarship yet refutes many of its conclusions, begins to rectify this situation. Presenting a close reading of the portrayal of the young couple before their ascent to the throne in Lope de Vega’s El mejor mozo de España, this essay considers how contrasts in their portrayals affect how they are viewed individually and as a couple. It concludes that Lope introduces subtle criticisms, in particular of Ferdinand, who is shown to be proud, materialistic, and immature. Additionally, it considers the characterisation of the secondary roles of King Henry IV and one of Isabella’s advisors, Don Gutierre, explaining how their different actions also serve to express reservations about Philip III and his foreign and domestic policies.