Hans-Werner Sinn (born 7 March 1948) is a German economist who served as President of the Ifo Institute for Economic Research from 1999 to 2016. He currently serves on the German ministry of economy’s advisory council. He is Professor Emeritus of Economics and Public Finance at LMU Munich.

After studying economics at the University of Münster from 1967 to 1972 and receiving his doctorate from the University of Mannheim in 1978, Sinn was awarded the venia legendi in 1983, also from the University of Mannheim.

Since 1984 Sinn has been full professor in the faculty of economics at LMU Munich, first holding the chair for economics and insurance, and from 1994 the chair for economics and public finance. During leaves of absence from the University of Mannheim and LMU Munich, he held visiting professorships (from 1978 to 1979 and from 1984 to 1985) at the University of Western Ontario in Canada. During sabbaticals he was also visiting researcher at the London School of Economics, as well as at the University of Bergen, Stanford University, Princeton University, and the Hebrew University of Jerusalem. The Otto von Guericke University Magdeburg, the University of Helsinki, the HHL Leipzig Graduate School of Management and the Prague University of Economics and Business have all awarded him honorary doctorates. Since 1988, he has been honorary professor of the University of Vienna, where he has given many lectures, and since 2017, he has been "permanent guest professor" at the University of Lucerne, Switzerland. In 2008 he was knighted with the Bavarian Maximilian Order for Science and Art, and in 2013, he was awarded the Ludwig Erhard Prize by the Ludwig-Erhard Foundation. From 1 February 1999 to 31 March 2016, Sinn was president of the Ifo Institute for Economic Research. The Leibniz Association, the umbrella organization for Germany's federally funded research institutions, extolled his turnaround of Ifo after having taken over the presidency at a highly critical juncture in the institute's history, bringing it back to a level of "very good, in some cases even excellent, research output" and turning it into "one of Europe's leading economic research institutes". In 2006 he became president of the International Institute of Public Finance, a position he held until 2009. From 1997 to 2000 Sinn headed the Verein für Socialpolitik, the association of German-speaking economists. He reformed the Verein für Socialpolitik and actively promoted the internationalization of economic science in the German-speaking countries. During his presidency he founded two journals – the German Economic Review and the Perspektiven der Wirtschaftspolitik -, initiated the Gossen prize to honor young economists that publish internationally and created a scholarship programme to financially support international conference presentations of young economists.

In 1991 he founded the Center for Economic Studies at LMU Munich. It was intended to serve as a visitors’ center for academic economists invited from all over the world for research and teaching in Munich. On the basis of CES he founded the first German Graduate Programme in Economics, which has been compulsory for all Ph.D. students of the faculty. Since 1999, when he became president of the Ifo Institute, CES and the Ifo Institute have met under an umbrella organisation, the CESifo Group, to build bridges between theoretical and empirical economic investigation and between researchers from all over the world. He founded the international CESifo Research Network. With its more than 1000 Professors of Economics from 63 countries it is among the largest international research networks of this kind. It publishes more than 500 research reports and organizes around 25 conferences per year. The Dutch Economist and former State Secretary of Education, Science and Culture of the Netherlands Rick van Ploeg honored Sinn's contribution to strengthening Economics as a subject in Germany and continental Europe.

Sinn is fellow of the National Bureau of Economic Research in Cambridge, Massachusetts, and was the first German-speaking economist to deliver the Yrjö Jahnsson Lectures in Helsinki (1999) and the Tinbergen Lectures in Amsterdam (2004).

Sinn topped a ranking of German economist provided by the Frankfurter Allgemeine Zeitung (FAZ) in 2013, 2014 and 2015. The FAZ's ranking named him "Germany's most influential economist of 2014", arguing that "no other economics researcher in Germany has such a high profile in the media and politics and is also active in research." Since his retirement in 2016 he has occupied the second rank. In the 2006 Handelsblatt ranking of German economists (Ökonomen-Ranking VWL), based on cross citations of SSCI papers in SSCI journals, Sinn ranked fourth. In a study by Ursprung and Zimmer, based on SSCI citations per author of the full oeuvre, Sinn ranked second of all German economists, after Nobel laureate Reinhard Selten. In the RePEc database he is the German economist most frequently quoted in academic works. In a survey conducted by the Financial Times Deutschland among more than 550 German economic experts, Sinn was one of the two professors in Germany (the other was Herbert Giersch) to attract a large following of academic pupils, and in terms of political influence he ranked only behind Bert Rürup at the top of the list of German professors. The British newspaper The Independent nominated him as one of the "ten people who changed the world" in 2011. In its latest evaluation of the Ifo Institute, the Leibniz Association praised Sinn as one of "Germany’s most renowned economists, who constantly succeeds in bringing the most varied economic issues to public debate".

Sinn has published 85 scholarly articles in refereed journals including the American Economic Review, the Quarterly Journal of Economics, the Journal of Monetary Economics and the Journal of Public Economics. He wrote 36 scholarly articles for refereed conference volumes, 23 scholarly comments for refereed journals and conference volumes, and about 200 academic policy papers in various outlets. He authored 11 refereed scholarly monographs and 10 non-refereed scholarly monographs. In addition, he has written numerous newspaper articles and given many interviews. Moreover, he has made longer contributions for radio and television and has made many talk-show appearances. More than twenty articles on his person have been published in German and foreign newspapers. His 2003 book "Ist Deutschland noch zu retten?" has stimulated policy discussion in Germany and influenced the Agenda 2010 reforms. With more than 100,000 copies in print, the book is one of the most popular public policy monographs in recent history. It has also been published in English as "Can Germany be Saved?" by MIT Press in 2007. As a reaction to the criticism of his book in the media, Sinn wrote a follow-up book in 2005, "Die Basarökonomie". His book the Green Paradox and his prior research on this topic triggered a worldwide debate, as did Sinn's research on TARGET2 balances, which is summarised in his book Die Target Falle. Sinn's book Casino Capitalism was named as one of the 50 best economics books of all time by Handelsblatt. His book "The Euro Trap: On Bursting Bubbles, Budgets, and Beliefs", published by Oxford University Press in 2014, reviews the effects of the adoption of the euro as a common currency and, in particular, the policy measures undertaken to combat the euro crisis. The book was hailed as "perhaps the most important scholarly book on the euro in at least a decade" by Kenneth Rogoff. He is also a regular contributor to Project Syndicate since 2002.

Since 1989 Sinn has served on the Advisory Council of the German Ministry of Economics, and represented the Free State of Bavaria on the Board of Supervisors of HypoVereinsbank for ten years.