Perhaps the best recorded examples of this are those men who served in the various national SS formations.

To start you off, SS-Charlemagne, SS-Nederland, SS-Wiking and SS-Nordland were all units that existed variously as regiments, brigades or divisions of the Waffen-SS. The units were raised to take volunteers from occupied northern Europe (France, The Netherlands and the wider Scandinavian region respectively, but there was considerable crossover) and several hundreds of thousands ended up serving.

These weren't simply propaganda outfits, designed for a convenient photo-op; men from Charlemagne were amongst the last troops to surrender around the Reich Chancellery and Hitler's bunker during the Battle for Berlin.

Having said that, some of these SS units were mainly a propaganda tool. The Britisches Freikorps and Indian Legion being leading examples

As for what happened to them...it depended largely on where they came from. Many men from Eastern Europe - for example Cossack volunteers - were executed or ended their lives in Soviet captivity. Others variously chose exile (many Dutch veterans seem to have chosen New Zealand), criminal prosecution or otherwise faded into obscurity.

This book may be a good starting point.

It's worth spending a few minutes looking through Google images, too. There is something eternally - and horrifyingly - surreal about, variously, the British Three Lions on an SS-uniform, or SS-volunteers in turbans and fezes.