Younger audiences will not have seen the Mission Impossible television show, nor have seen Landau as a Roman in Cleopatra. most likely they would have seen him in Ed Wood as Bela Lugosi in his final days.
A skilled an actor as he was, Landau also taught acting. His influence extended far beyond his roles (and there were times when he was not in front of the camera), but his influence extended throughout the profession.
I smiled when I read in the NYT story that he had to learn the Hungarian accent for playing Lugosi. That's what I heard growing up from my father's family. What's to learn, I asked?