Despite Tristan’s place as a cornerstone of the operatic repertory, there has been surprisingly little scholarship on King Mark, whom scholars often overlook in favour of the title characters. This study examines Wagner’s adaptation of his source, the Tristan of Gottfried von Strassburg, to construct a character that represents the courtly chivalric society of the opera in opposition to the new order represented in Tristan’s passionate pursuit of love and, ultimately, of death. Building on literary scholarship of the Tristan tradition, this study explores issues of duality and decline in Mark’s character and the elements of his chivalric friendship with Tristan within the homosocial constructs of the courts. Through his use of traditional operatic lament form, associative orchestration, and text expression, Wagner constructs a king who is more nuanced that any of his predecessors: one cleansed by tragedy and capable of forgiveness.