Former German foreign minister Hans-Dietrich Genscher has died at the age of 89, his office has announced.
He died on Thursday night at his home in the town of Wachtberg-Pech, near Bonn, of heart failure, a statement said.
Mr Genscher served as West German foreign minister and vice chancellor from 1974 until reunification in 1990, continuing on in the role until 1992.
He was also chairman of his liberal FDP party from 1974 to 1985.
During the Cold War, Mr Genscher's policy of detente towards the East and his early recognition of then Soviet leader Mikhail Gorbachev's desire for change is credited with paving the way for Germany's reunification.
He was also a strong advocate of European unity.
Announcing his retirement from Parliament in 1998, he said: "European unity is the answer to the mistakes of the Germans and of European history. It is the answer to a terrible world war. These reasons stand even today."
Chancellor Angela Merkel's deputy spokesman, Georg Streiter, paid tribute to Mr Genscher, saying: "He was a statesman who influenced the fate of Germany like few others. He was a great European and a great German."
One of Mr Genscher's most celebrated moments was in 1989 at the German embassy in Prague where he addressed thousands of East Germans desperate to head west.
Announcing a deal with the Czech communist government allowing them safe passage, he said: "We have come to you to tell you that today your departure..."
The rest of the sentence was drowned out by cheers.