Strauss, Salome, Final Scene, part 1 (of 3, and I highly recommend watching the others,. specifically part 2, it’s my favorite)
An operatic adaptation of the play by Oscar Wilde. It tells of the beheading of John the Baptist, though it takes several (dramatic) liberties.
It is easily the most disturbing opera I’ve ever watched. Salome’s character is so ridiculously dark, but you can’t look away.