This introduction provides an overview of the rivalry between Saudi Arabia and Iran. Conflict across the Middle East has routinely been framed as a consequence of proxy wars, such as the conflict in Iraq, Libya, Syria, Yemen, albeit playing out in different ways. These proxy wars are often found as features of the rivalry between Saudi Arabia and Iran, yet the ways in which Saudi Arabia and Iran develop relationships with local actors points to a more complex set of relationships than the model typically understood within a ‘proxy relationship’. Indeed, as work done by the Sectarianism, Proxies and De-sectarianization (SEPAD) project has observed, perhaps most clearly in a special issue edited by Edward Wastnidge and myself, trans-state relationships between states – in this case Saudi Arabia and Iran – and non-state actors are products of time and space, meaning that a range of factors influence the relationships, producing a number of different outcomes. This includes some local actors possessing far more agency than is often typically assumed, as observed by Amal Saad in the case of Hizbullah. This ability to exert influence independent of the patron actor’s wishes appears to push the borders of the concept. The introduction closes with a discussion of the foreign policies of Saudi Arabia and Iran.