Guillermo Uribe-Holguín
Born: 17 March 1880, Bogotá (Colombia)
Died: 26 June 1971, Bogotá (Colombia)
Richard Wagner
Born: 22 May 1813, Leipzig (Germany)
Died: 13 February 1883, Venezia (Italy)
Iannis Xenakis (1922 - 2001)
Yaras, Ramunas (1971-)
Yashiro, Akio (1929-1976)
Yi, ManBang (-)
Yon, Pietro (1886-1943)
de Yradier, Sebastián (1809-1865)
Ysaÿe, Eugène (1858-1931)
Yun, Isang (1917-1995)
Zimmermann, Bernd Alois
I don't remember whether we've done this category before, but - Broadway or movie musicals.
Annie Get Your Gun
Iolanthe (or doesn't light opera count?)
The Kids are All Right (the Who) - a musical movie, might not be exactly what you were looking for, but it's a K. :-D
