Excerpts from Books and Wikipedia
"Gustav III (1771–1792)
Usually called the Theatre King, Gustav III was a keen patron of the arts, and founded the first opera in Stockholm in 1782, the Swedish Academy and the Royal Academy of Music. His reign was not popular with the high nobility, however, and opposition culminated in a conspiracy in 1792, when he was shot at a masked ball held at the opera. He died shortly after."
[https://sweden.se/society/history-of-sweden/]