Michael Caine, who is still active today as an octogenarian once quipped, "You don't retire in this business, the business retires you". Interestingly, he was in every film directed by Christopher Nolan, since he took on the role of Bruce Wayne's butler Alfred in Batman Begins (2005). He may not have appeared in Dunkirk (2007), but he did a voice-over in that movie. To know more about his life story, watch: "Discovering - Michael Caine".