This dissertation examines the relationship between the early Spanish Empire and the worldwide phenomenon of colonialism by analyzing an often-overlooked bureaucratic office, that of corregidor, a position of medieval origin that was installed throughout the Spanish realms under Habsburg rule, and one that played a special role in the vast and rich Viceroyalty of Peru immediately after conquest. This work posits a reinterpretation of the relationship between colonial Spanish America and the larger empire, known then as the Spanish Monarchy, by treating Spanish South America not as an isolated unit or proto-national space, but rather as part of a broader Atlantic and even globalized world, constantly shaped and reshaped by interactions between colony and metropole. As a result of transatlantic interactions and often fraught negotiations, I propose, Greater Peru grew apart from Castile, its nominal center, even as Castile was also changed, its mode of governance forever altered. By tracing how the position of corregidor evolved in early Peru while tracking its parallel development in Castile, this study challenges traditional understandings of how power flowed across oceans, and thus how colonialism ended up persisting throughout Spanish America for nearly three centuries.