Rhinoceros by Eugene Ionesco is a play written in 1959. The story is that people are shocked to see a Rhinoceros charge down the street. Soon it emerges that people are turning into Rhinoceros. Eventually everyone has turned into a rhino apart from Berenger. He wants to, he tries to, but he is for some reason unable to become a rhinoceros. It is part of the Theatre of the Absurd - but it is not absurd, it is an allegory for conformity.
A film has been made and several stage plays - but I imagine that none have done it justice. At one stage around 1963/4 plans were made to make it into a film staring the Comedian Tony Hancock as Berenger. In his prime, he would have been brilliant, perhaps even at the time, he would have been great, but for various reasons the film wasn't made.
In these days of computer generated special effects, a film version would be more fantastic than ever.
In the lead role, someone like Jack Dee.