Lerner & Lowe based My Fair Lady on Pygmalion and Camelot on Once and Future King, Oklahoma on a non-musical play and King & ISound of Music* were highly fictionalized musicalizations of highly fictionalized previous film versions of somewhat true stories (Sound of Music was based on a German filmwhich was based on Maria von Trapp’s memoirs) and South Pacific on stories by James Michener. Kander and Ebb based Cabaret on various works by Isherwood [ultimately] and Chicago on a non-musical movie/play and novel and Kiss of the Spider Woman on the novel, Fiddler on the Roof was based on the short stories of Sholem Aleichem, Les Miserables and Wicked and Ragtime on the novels of those names, Miss Saigon is an updating/adaptation of Madame Butterfly as Rent is of La Boheme, and most of the musicals produced in the last decade are musicalizations of movies (with Hairspray being a musical movie based on a musical play based on a non musical movie and The Color Purple soon to be a musical movie based on a musical play based on a novel that inspired/was cross pollenated by a major non-musical motion picture).
Have there been any successful musicals that have been completely original? By this I mean they were not based on a novel, non-musical play, or previous work but were an original story with original characters designed specifically for the musical theater? Gilbert and Sullivan I’m pretty sure would qualify- some of their works anyway- but surely there’s something more recent.
I’m not making judgment I should ad: I loved many of the works above and few if any of Shakespeare’s plays (which I consider a sort of “spoken musical”) were original in plot, but I’m just curious if any characters/stories began as musicals.