I'm currently reading around the edges of Fahrenheit 451, as part of a study of both Bradbury's work and Francois Truffaut's 1966 film adaptation.
I just finished Arthur Koestler's novel Darkness at Noon, which is a fascinating inside look at post-revolutionary Russia - although Koestler, writing in 1940, carefully avoids specifying any of the countries where the events of the novel take place. I found the novel quite chilling and atmospheric, but was constantly reminded of George Orwell's Animal Farm (1945) AND Nineteen Eighty-Four (1949). I understand that Orwell was familiar with Koestler's work, and even wrote an essay about him. I will have to track this down.
Immediately after finishing the novel, I moved on to Sidney Kingsley's 1951 play based on Koestler's novel. I was pleasantly surprised to find that the hardcover edition of the play includes photographs from the original Broadway production. The original cast of the play included Claude Rains (in the lead role as Rubashov), and Kim Hunter.
All of which brings me back to Bradbury. We know that Bradbury knew Koestler's novel and that he saw Kingsley's play. In fact, he was once quoted as saying that he thought Koestler captured aspects of totalitarianism more accurately than did either Orwell or Aldous Huxley.
Bradbury was also an admirer of Claude Rains, although the only professional connection between them (that I can think of) is the Alfred Hitchcock Presents adaptation of Bradbury's "And So Died Riabouchinska". Bradbury's admiration of Rains is referred to in this account of Terry Pace's 2009 production Claude Rains: An Actor's Voice.