Sven T. Siefken is a political scientist, political advisor and management consultant. His special research focus is on parliaments.

He is Professor of Political Science at the German Federal University of Applied Administrative Sciences and Senior Research Fellow at the Institute for Parliamentary Research (IParl) in Berlin, Germany. He is also a visiting professor at Colorado College, USA, and an Associated Lecturer at Georgetown University in Washington, D.C. (2023). Siefken is Vice Chair of the Research Committee of Legislative Specialists (RC08) of the International Political Science Association and editor of the German Journal of Parliamentary Affairs (Zeitschrift für Parlamentsfragen).

His current work investigates coalition politics, parliamentary committees, parliaments in the pandemic and the future of democratic representation.