In the UK,  Brian Eno, who experimented with synths first with Roxy Music and later in his solo career was influenced by the krautrock bands and collaborated with Harmonia and Cluster.

Can was experimenting with ethnic sounds and they all come from different backgrounds. Bass player Holger Czukay together with Irmin Schmidt founded Can in Cologne. Holger started his career as a music teacher. Irmin Schmidt was a classical pianist, Michael Karoli was familiar with gypsy music and drummer Jaki Liebezeit came from the jazz scene. After the band broke up Holger Czukay became a solo artist and was accompanied in most cases by members of Can.

Kraftwerk was founded by Ralf Hütter and Florian Schneider in Düsseldorf first under the name Organisation and then Kraftwerk. The Albums Tone Float (Organisation), Kraftwerk 1 and Kraftwerk 2 were very experimental and they were still searching for their own unique sound. These albums and "Ralf und Florian" are difficult to obtain nowadays on CD. When they became more commercial they started translating their albums in english.

Recently I discovered Cluster. Dieter Moebius, Hans-Joachim Roedelius and Conrad Schnitzler formed Kluster in 1969 in Berlin. After Conrad left the band the name was changed to Cluster spelled with a C. Conny Plank joined the band to replace Conrad on their first album as Cluster but left also. Cluster continued as a duo. Their breakthrough came in 1974 with "Zuckerzeit". In 1976 they recorded an album with Brian Eno "Tracks and Traces" but was not released until 1997. Another album was recorded with Eno and was released as "Cluster & Eno" in 1977. The third album they did with Eno "After the Heat" featured a much wider range of styles and is the best they did with Eno.

Nektar was formed in Hamburg in 1969. Their debut "Journey to the Centre of the Eye" from 1971 was a single song of 40 minutes. This album was very experimental and therefore belongs to the krautrock genre. Then they moved more to symfo rock in style. See a review about their album "Down To Earth" 1974 here.

Another band that had a big influence on David Bowie was Neu! Formed in 1971 in Düsseldorf by Klaus Dinger and Michael Rother following their departure from Kraftwerk. Their third album "Neu! '75" included a song called "Hero". Bowie used the title for his song "Heroes" while the Bowie albums "Low" and "Heroes" were influenced by krautrock and particulary Neu! Produced by Brian Eno.

Here is my top 5 of krautrock bands:

Can's best albums are for me "Future Days", "Soon Over Babaluma" and "Flow Motion". Kraftwerk's best albums are "Autobahn", "Radio Activity" and "The Man Machine". Cluster's best albums are "Sowiesoso", "Grosses Wasser" and "Curiosum". Nektar's best albums are "A Tab in the Ocean",  "Remember The Future" and "Down To Earth". Neu! only released 4 albums of which "Neu! '75" is their best.