Jimi Hendrix and Tiny Tim
Laibach and Kate Bush
NIN and Stryper
Tori Amos and Ronnie James Dio
John Lennon sings backup on Bowie’s version of Across The Universe from Young Americans: most audibly Lennon on the fadeout, especially through headphones.
Yoko Ono was going to collaborate on something with the B-52’s, whose singing style, at least in the early records, was inspired by Yoko’s, er, eccentric vocalizations.