Horst Siebert (20 March 1938 – 2 June 2009) was a German economist. He was a member of the German Council of Economic Experts from 1990 to 2003. Siebert also served as a member of both the Group of Economic Analysis (GEA) and the Group of Economic Policy Analysis (GEPA), a number of "European economists who advise the European Commission’s president." From 2002 to 2004, as a member of GEA, he advised EU President Romano Prodi. From 2005 to 2007, as a member of GEPA, he advised EU President Jose Manuel Barroso Siebert spent most of his academic career at the University of Kiel, where he held the chair for economic theory from 1989 to 2003.