The King Of...

The first name I thought of was Nile Rodgers. 

It's an interesting question. At least to me, because one could argue that the King of Disco (without a definition of what a "King" would be) may not be a composer, artist, or producer but a DJ. 

Tony Manero from Saturday Night Fever.

You can’t bring up disco without mentioning Donna Summer. Not a king but a queen for sure.

czar-you left off King of the Delta Blues Singers.Also I have some question on King Of Pop.It's a self proclaimed title,that's somewhat akin to giving yourself a nickname.I never felt it worked that way.

If you're discussing disco I dread to think what's in your record collection...