One important thing to note about great casting in a biographical film is that it does not always result in a great biopic. One of the strengths of film is that it's such a collaborative medium, but this is also why uninspired directing or a staid screenplay can so easily threaten an inspired performance. There are a few examples of that on this list, but in every case the exceptional work of the star still makes the picture worth watching. It’s also worth noting that while Hollywood has a long history of producing biopics, there are many more instances of actors portraying real people in films that aren't strictly about that person. This list is limited to genuine biopics.