Cluster were a German musical duo consisting of Hans-Joachim Roedelius and Dieter Moebius, formed in 1971 and associated with West Germany's krautrock and kosmische music scenes. Born from the earlier Berlin-based group Kluster, they relocated in 1971 into the countryside village of Forst, Lower Saxony, where they built a studio and collaborated with musicians such as Conny Plank, Brian Eno, and Michael Rother; with the latter, they formed the influential side-project Harmonia. After first disbanding in 1981, Cluster reunited several times: from 1989 to 1997, and from 2007 to 2010.

Hans-Joachim Roedelius is a German electronic musician and composer, known as a co-founder of the influential 'kosmische' groups Cluster and Harmonia. He is notable for his prolific discography either as himself, as part of a band, or in collaboration with other artists. He has more than 100 releases with his name. He also performed in the ambient jazz trio Aquarello, and released several solo studio albums.