It wasn’t till years after I first saw the movie that this occurred to me, but then it began to niggle a bit. Father Karras is of Greek extraction, seemingly on both sides, since his mother appears to be an immigrant and his surname is also Greek. The thing is that only about 1% of the Greek population is Roman Catholic. This certainly doesn’t preclude the possibility of a Roman Catholic priest with Greek ancestry, but it makes it unusual enough that one might wonder if there was some significance to it. Has anyone ever heard an explanation for why Blatty went this way? It may be as simple as that he knew such a priest. It just certainly seems a departure from the more typical Italian, Irish, Polish, Spanish, French, etc.