In recent years the Bill and Melinda Gates Foundation has emerged as this era’s most renowned, and arguably its most influential, global health player. A century ago, the Rockefeller Foundation—likewise founded by the richest, most ruthless and innovative capitalist of his day—was an even more powerful international health actor. This article reflects critically on the roots, exigencies, and reach of global health philanthropy, comparing the goals, paradigms, principles, modus operandi, and agenda-setting roles of the Rockefeller and Gates Foundations in their historical contexts. It proposes that the Rockefeller Foundation’s early 20th century initiatives had a greater bearing on international health when the field was wide open—in a world order characterized by forceful European and ascendant U.S. imperialism—than do the Gates Foundation’s current global health efforts amidst neoliberal globalization and fading U.S. hegemony. It concludes that the Gates Foundation’s pervasive influence is nonetheless of grave concern both to democratic global health governance and to scientific independence—and urges scientists to play a role in contesting and identifying alternatives to global health philanthrocapitalism.