Helmut Schmidt, who served as West German Chancellor from 1974 to 1982, has died aged 96, his office says.
Mr Schmidt, who was a Social Democrat, was an architect of the European Monetary System, which linked EU currencies and helped pave the way to the euro. He also helped to consolidate Germany's post-war economic boom.
Chancellor Angela Merkel hailed him as a "political institution" in Germany.
He is seen as one of the most popular German leaders since WWII.
Mr Schmidt died on Tuesday afternoon in his home city of Hamburg, his doctor Heiner Greten was quoted as saying by German media.
The doctor provided no further details.