November 2, 1946 - April 20, 2001: Age 54
Italian maestro Giuseppe Sinopoli was conducting Verdi's Aida at the Berlin Opera House when he collapsed during the third act. The performance was stopped and the audience, cast, and orchestra was sent home. Attempts to resuscitate him on the scene were unsuccessful, and he died. Ironically, Aida was the first work he conducted as well as his last: it was the work with which he made his debut in 1972.
Source: New York Times