The European Union is a political entity characterized by multilevel and nested negotiations, including the European, national, and, often, regional levels of decision-making. Only a select few have risen to the top of European history, having managed to influence and shape the course of the European integration process by managing complex and multifaceted negotiations and directing them to the desired outcome. Jacques Delors, President of the European Commission from 1985 to 1995, was one such legendary figure, very much associated with historical decisions at critical junctures, more importantly, the Single Market in the context of the Single European Act and the Economic and Monetary Union (EMU), nested within the broader negotiations that led to the Treaty of Maastricht. This chapter aims to provide a comprehensive portrait of Jacques Delors as a negotiator, providing insights into his engagement and role in negotiations that have shaped the EU as we know it nowadays.