Robert John Guest was a New Zealand-Australian actor, television personality and host and singer, who started his career in pop music in New Zealand, before becoming best known for his work in Australian musical theatre, particularly in various productions of The Phantom of the Opera. He played the lead for a record-breaking 2,289 performances over seven years, more than any other performer.

The Phantom of the Opera is a musical with music by Andrew Lloyd Webber, lyrics by Charles Hart, additional lyrics by Richard Stilgoe and a libretto by Lloyd Webber and Stilgoe. Based on the 1910 French novel of the same name by Gaston Leroux, it tells the tragic story of a beautiful soprano, Christine Daaé, who becomes the obsession of a mysterious, masked musical genius living in the subterranean labyrinth beneath the Paris Opéra House.