Although a growing number of academic studies show the negative impact of populism on democracy, there are very few analyses that examine the ways in which populist forces can foster processes of autocratization. In this contribution, we aim to address this research gap, putting particular emphasis on what happens when populist actors have enough electoral power to conquer executive office with the capacity to stay in power for a long period of time. We argue that under these circumstances, populist forces tend to affect diagonal, horizontal, and vertical accountability, setting in motion a process of democratic backsliding. We illustrate this argument with evidence from an instance of right-wing populist rule in Eastern Europe (Viktor Orbán in Hungary) and an instance of left-wing populist rule in Latin America (Hugo Chávez in Venezuela). The contribution concludes by summarizing the main ideas discussed and discussing avenues for future research on this topic.