Unexpected song collaborations that are ace

[Scout2016]

AIBU to ask for song recommendations where the song is ace but you wouldn't have imagined the artists hanging out together? Ideally a full on proper collaboration, not just featuring. So not Tom Petty and Stevie Nicks, who you'd expect to have been mates, or Metallica and Marianne Faithful because she just "la la la la"s along to a very much Metallica song.
I'll go Sinead O'Connor and Willie Nelson's "Don't Give Up" and Iggy Pop and Kate Pierson "Candy."

C'est si bon by Thomas Dutronc (Françoise Hardy and Jacques Dutronc's son) with Iggy Pop and Diana Krall. Great jazzy collaboration in English and French.

Pavarotti did some cracking collaborations - his duet with Tracy Chapman on “Baby Can I Hold You Tonight” is sublime.

Eminem has some amazing and unexpected collaborations under his belt!

Elton John, Ed Sheeran, Dido & Rhianna to name a few.

Just discovered Marc Almond and Nico song which checking out earlier Gene Pitny recommendation. Not sure it works but it's interesting!
"Easy" by Lorde and Son Lux is brilliant. Don't know how unexpected as don't know Son Lux at all but it's fantastic.

I quite like ed Sheeran with 50 cent and Eminem. I think it's called remember the name

"Barcelona" is wonderful, gives me goosebumps.

This isn't an official collaboration and I haven't googled but it may be available on YouTube somewhere. A few years ago I was listening to Chris Evans; breakfast show (not sure if it was in his Virgin or Radio 2 days) and every Friday he'd have a bunch of celebrities in. This particular day, he had Nile Rodgers and Mark Knopfler and they jammed together. Apparently they'd never met before. It was MAGIC. (I'd say it was in the aftermath of Get Lucky, timewise).

Apparently Lulu was there as well www.bbc.co.uk/programmes/p02mdjct

@Scout2016 I absolutely love Skin and skunk anansie, they were my first proper concert at 16! There is something magical about her voice, her range is incredible.

When youre gone Bryan Adams and mel c

Another vote here for Barcelona. Both very talented musicians and it really worked.

On the subject of jamming sessions, at the end of each WOMAD festival they have a perfomance where they bring together a group of instruments. I was lucky enough to attend one which was harps (African kora, Chinese, Iraqi, I think?) They met backstage half an hour before the performance and it was magic. I also attended another one with percussionists. How they come together I'll never understand, but it works. Usually the only language they have in common is music