Cluster was a German experimental musical group who influenced the development of contemporary popular electronic and ambient music. They have recorded albums in a wide variety of styles ranging from experimental music to progressive rock, all of which had an avant-garde edge. Cluster was active from 1971 until 2010, releasing a total of 15 albums, including two collaborations with Brian Eno. Musician, writer and rock historian Julian Cope places three Cluster albums in his Krautrock Top 50 and "The Wire" places Cluster's self-titled debut album in their "One Hundred Records That Set The World On Fire". After a decade long hiatus Cluster reunited in April, 2007.

They performed at the opening of documenta 12, a major exhibition of modern and contemporary art held every five years in Kassel, Germany on June 15, 2007. In late 2007 Cluster performed at concerts across Europe and played the United States in 2008 for the first time since 1996.

Cluster disbanded at the end of 2010. Their final concert was on December 5 of that year.

In 2011, Roedelius recruited Onnen Bock to reactivate Cluster under the name of "Qluster". After the release of their debut trilogy "Rufen - Fragen - Antworten" ("Calling - Questioning - Responding") in the form of a piano record, a live documentary and a normal record, Qluster will release their fourth record "Lauschen" ("Eavesdropping") in January 2013.