Peter Andreas Grünberg (born 18 May 1939) is a German physicist, and Nobel Prize in Physics laureate for his discovery with Albert Fert of giant magnetoresistance which brought about a breakthrough in gigabyte hard disk drives.

Grünberg was born in Pilsen, Bohemia, which at the time was in the Nazi-occupied Protectorate of Bohemia and Moravia (now the Czech Republic) to the Sudeten German family of Anna and Feodor A. Grünberg which first lived in Dysina (Dýšina) to the East of Pilsen.

After the war, the family was interned, the parents were brought to a camp. His father, a Russia-born engineer who since 1928 worked for Škoda, died on 27 November 1945 in Czech imprisonment and is buried in a mass grave in Pilsen which is also inscribed with Grünberg Theodor † 27. November 1945. His mother Anna (who died in 2002 aged 100) had to work in agriculture and stayed with her parents in the Petermann house in Untersekerschan (Dolní Sekyřany), where her children (a sister was born in 1937) were brought to later. The remaining Grünberg family, like almost all Germans, was expelled from Czechoslovakia in 1946. Seven year old Peter came to Lauterbach, Hesse where he attended gymnasium.

Albert (Bert) Fert (born 7 March 1938 in Carcassonne, Aude) is a French physicist and one of the discoverers of giant magnetoresistance which brought about a breakthrough in gigabyte hard disks. He is currently an emeritus professor at Université Paris-Sud in Orsay and scientific director of a joint laboratory ('Unité mixte de recherche') between the Centre national de la recherche scientifique (National Scientific Research Centre) and Thales Group. Also, he is an Adjunct professor of physics at Michigan State University. He was awarded the 2007 Nobel Prize in Physics together with Peter Grünberg.

Fert graduated in 1962 from the École Normale Supérieure in Paris. He received his master's degree in 1963 at the University of Paris, and earned his PhD in 1970 at the Université Paris-Sud.

In 1988 Fert discovered the Giant magnetoresistance effect (GMR) in multilayers of iron and chromium which is recognized as the birth of spintronics; GMR was simultaneously and independently discovered by Peter Grünberg from the Jülich Research Centre. Since 1988, Albert Fert has made contributions to the field of spintronics.