There's no question that the TV show Mad Men became such a success thanks to the hard work of the terrific ensemble cast. However, it's also inarguable that Don Draper, played by Jon Hamm, is the lynchpin of the series. The protagonist, antihero, and nuanced character whom we follow from the beginning of Mad Men keeps viewers invested in the story, and was a huge selling point for the show. This makes it all the more interesting to contemplate what the series would've been like if someone other than Hamm had stepped into the role.