I'm really looking outside the UK (the nation, not the band) for this, particularly in the Italian scene ... (btw, searched the forums and can't find a similar topic)

Now we all know John Wetton was in Family, Roxy Music, King Crimson, Uriah Heep, UK, Asia and Wishbone Ash (plus a couple of others I'm sure) and that his fellow band members in UK, Bill Bruford (Yes, King Crimson, Pavlov's Dog, National Health, Bruford) and Allan Holdsworth (Tempest, Gong, Soft Machine, Bruford) were also in many bands. There were also numerous overlaps among the incestous Canterbury scene (Richard Sinclair for example was in Caravan, Hatfield And The North and Camel).

But what overlaps do we have in non-UK bands?

I know in Germany, Renate Knaup was in both Amon Duul II and Popul Voh, the Neu! guys were initially with Kraftwerk and that Klaus Schulze was in Ash Ra Tempel and Tangerine Dream before going solo. The only Italian example I know is Bernardo Lanzetti who was with both Acqua Fragile and PFM.

What other examples can you think of? And with which band do you think the artist did their best work?

I realise you are looking outside the UK, but Clive Nolan has to be mentioned... he's in Arena, Shadowlands, Strangers On A Train & Nolan & Wakeman.  He also plays keys for Pendragon, Ayreon, Martin Darvill, and does stuff with Damian Wilson & Tracey Hitchings (Landmarq)... don't think the guy sleeps very much!

His best work is undoubtedly with Arena, tho...

In Germany both Helmut Hattler (bass) and Ingo Bischof (keyboards) played for both Kraan and Guru Guru. Ingo Bischof also played for Karthago, where he played with bass player Gerald Luciano Hartwig. Hartwig also played for Guru Guru and Embryo. Chris Karrer of Amon Düül 2 also played for Embryo. Roland Schaeffer of Brainstorm played for Embryo as well as Guru Guru. Chriian Burchard of Embryo also played for Amon Düül 2. Drummer Dieter Serfas of Amon Düül 2 also played for Embryo once. In the whole, Guru Guru, Kraan, Embryo, And Amon Düül 2 are some family maze. Daniel Fischelscher, drummer of Amon Düül 2, played guitar and drums on a few Popol Vuh albums. Roman Bunka played for Embryo and Aera and had a band of his own, in which Hartwig and Aera dummer and keyboarder Freddy Setz played. Many Neumeier of Guru Guru played with Dieter Moebius and Achim Roedelius of Cluster and Harmonium. Then there are short-lived projects like Highdelberg and Liliental, that feature members of Kraan, Guru Guru and Harmonium plus a few others. Not to forget Missus Beastly and Munju, who are involved in this family maze too. One of the reasons for this closeness appears to be that bands like Kraan, Guru Guru and Amon Düül 2 lived as alternative communities who were naturally interested in other alternative communities. The list is by no means complete, I could go on endlessly.

There is a German tv-movie from 1980, which follows the Roman Bunka band on their tour, and in one part of the movie they meet their friends of Embryo, and of course immediately a session starts. I have the movie on video, through connections; the movie is only so-so, but the music is fantastic!

Well with Sweden, Roine Stolt has been all over the place in bands such as Kaipa, The Flower Kings, Karmakanic, Par Lindh Project, Swedish Family, The Tangent, Triangulus and Transatlantic.

I think Stolt's best work was in Kaipa and The Flower Kings though the new stuff isn't as good as his 70's and 90's works.

Can't think of too many from Italy, though some band members from The New Trolls went on to other bands such as Ibis and Nova.

FuzzyDude wrote: After King Crimson fell apart the first time, Robert Fripp played with every prog band in the seventies at some point. I nominate him for biggest prog whore.

Agree!

Also, Phil Collins have played in several bands: Genesis, Brand X, Flaming Youth, Steve Hackett's first solo album - Voyage of The Acolyte, On Peter Gabriels first albums, etc.