Theatre star Rob Guest has died in Melbourne after suffering a massive stroke.

Guest, 57, who had been starring in the musical Wicked, was admitted to Melbourne's St Vincent's Hospital Wednesday night, a spokeswoman for the production said.

Guest was born in Britain but enjoyed fame as a pop star in New Zealand in the 1970s and 1980s and spent a decade in Las Vegas.

His stage musical career took him to Australia where he starred in Les Miserables and The Phantom of the Opera.

He was awarded an OBE for his services to the New Zealand entertainment industry.

Guest was the world's longest serving Phantom having played the role a record 2289 performances over seven years in front of Australian and New Zealand audiences.

It is understood his New Zealand family was at his beside when he died.